Publications by authors named "William Snyder"

79 Publications

Dynamic functional connectivity profile of the salience network across the life span.

Hum Brain Mapp 2021 Jul 26. Epub 2021 Jul 26.

Department of Psychology, University of Miami, Coral Gables, Florida.

The insular cortex and anterior cingulate cortex together comprise the salience or midcingulo-insular network, involved in detecting salient events and initiating control signals to mediate brain network dynamics. The extent to which functional coupling between the salience network and the rest of the brain undergoes changes due to development and aging is at present largely unexplored. Here, we examine dynamic functional connectivity (dFC) of the salience network in a large life span sample (n = 601; 6-85 years old). A sliding-window analysis and k-means clustering revealed five states of dFC formed with the salience network, characterized by either widespread asynchrony or different patterns of synchrony between the salience network and other brain regions. We determined the frequency, dwell time, total transitions, and specific state-to-state transitions for each state and subject, regressing the metrics with subjects' age to identify life span trends. A dynamic state characterized by low connectivity between the salience network and the rest of the brain had a strong positive quadratic relationship between age and both frequency and dwell time. Additional frequency, dwell time, total transitions, and state-to-state transition trends were observed with other salience network states. Our results highlight the metastable dynamics of the salience network and its role in the maturation of brain regions critical for cognition.
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http://dx.doi.org/10.1002/hbm.25581DOI Listing
July 2021

A parametric approach to the acquisition of syntax.

Authors:
William Snyder

J Child Lang 2021 Jul 19:1-26. Epub 2021 Jul 19.

University of Connecticut.

Three case-studies, using longitudinal records of children's spontaneous speech, illustrate what happens when a child's syntax changes. The first, examining acquisition of English verb-particle constructions, shows a near-total absence of commission errors. The second, examining acquisition of prepositional questions in English or Spanish, shows that children (i) may go as long as 9 months producing both direct-object questions and declaratives with prepositional phrases, before first attempting a prepositional question; and (ii) at some point, abrubtly begin producing prepositional questions that are correctly formed for the target language. The third case study shows that in children acquiring English, the onset of verb-particle constructions occurs almost exactly when that child begins using novel noun-noun compounds. After a discussion of the implications for the nature of syntactic knowledge, and for the mechanisms by which it is acquired, two examples are presented of as-yet untested acquisitional predictions of parametric proposals in the syntax literature.
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http://dx.doi.org/10.1017/S0305000921000465DOI Listing
July 2021

Alternative prey and farming system mediate predation of Colorado potato beetles by generalists.

Pest Manag Sci 2021 Jul 11. Epub 2021 Jul 11.

Department of Entomology, University of Georgia, Athens, GA, USA.

Background: Biological control by generalist predators can be mediated by the abundance and biodiversity of alternative prey. When alternative prey draw predator attacks away from the control target, they can weaken pest suppression. In other cases, a diverse prey base can promote predator abundance and biodiversity, reduce predator-predator interference, and benefit biocontrol. Here, we used molecular gut-content analysis to assess how community composition altered predation of Colorado potato beetle (Leptinotarsa decemlineata (Say)) by Nabis sp. and Geocoris sp. Predators were collected from organic or conventional potato (Solanum tuberosum L.) fields, encouraging differences in arthropod community composition.

Results: In organic fields, Nabis predation of potato beetles decreased with increasing arthropod richness and predator abundance. This is consistent with Nabis predators switching to other prey species when available and with growing predator-predator interference. In conventional fields these patterns were reversed, however, with potato beetle predation by Nabis increasing with greater arthropod richness and predator abundance. For Geocoris, Colorado potato beetle predation was more frequent in organic than in conventional fields. However, Geocoris predation of beetles was less frequent in fields with higher abundance of the detritus-feeding fly Scaptomyza pallida Zetterstedt, or of all arthropods, consistent with predators choosing other prey when available.

Conclusion: Alternative prey generally dampened predation of potato beetles, suggesting these pests were less-preferred prey. Nabis and Geocoris differed in which alternative prey were most disruptive to feeding on potato beetles, and in the effects of farm management on predation, consistent with the two predator species occupying complementary feeding niches.
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http://dx.doi.org/10.1002/ps.6553DOI Listing
July 2021

Complex life histories predispose aphids to recent abundance declines.

Glob Chang Biol 2021 Jul 3. Epub 2021 Jul 3.

Department of Entomology, University of Georgia, Athens, GA, USA.

Many animals change feeding habits as they progress through life stages, exploiting resources that vary in space and time. However, complex life histories may bring new risks if rapid environmental change disrupts the timing of these switches. Here, we use abundance times series for a diverse group of herbivorous insects, aphids, to search for trait and environmental characteristics associated with declines. Our meta dataset spanned three world regions and >300 aphid species, tracked at 75 individual sites for 10-50 years. Abundances were generally falling, with median changes of -8.3%, -5.6%, and -0.1% per year in the central USA, northwestern USA, and United Kingdom, respectively. Aphids that obligately alternated between host plants annually and those that were agricultural pests exhibited the steepest declines, relative to species able to persist on the same host plant year-round or those in natural areas. This suggests that host alternation might expose aphids to climate-induced phenology mismatches with one or more of their host plant species, with additional risks from exposure to insecticides and other management efforts. Warming temperatures through time were associated with milder aphid declines or even abundance increases, particularly at higher latitudes. Altogether, while a warming world appeared to benefit some aphid species in some places, most aphid species that had time-sensitive movements among multiple host plants seemed to face greater risk of decline. More generally, this suggests that recent human-induced rapid environmental change is rebalancing the risks and rewards associated with complex life histories.
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http://dx.doi.org/10.1111/gcb.15739DOI Listing
July 2021

M. S. Crossley et al. reply.

Nat Ecol Evol 2021 05 5;5(5):595-599. Epub 2021 Apr 5.

Department of Biology and Health Sciences, Hendrix College, Conway, AR, USA.

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http://dx.doi.org/10.1038/s41559-021-01429-9DOI Listing
May 2021

Selection for high levels of resistance to double-stranded RNA (dsRNA) in Colorado potato beetle (Leptinotarsa decemlineata Say) using non-transgenic foliar delivery.

Sci Rep 2021 Mar 22;11(1):6523. Epub 2021 Mar 22.

Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN, 37996, USA.

Insecticidal double-stranded RNAs (dsRNAs) silence expression of vital genes by activating the RNA interference (RNAi) mechanism in insect cells. Despite high commercial interest in insecticidal dsRNA, information on resistance to dsRNA is scarce, particularly for dsRNA products with non-transgenic delivery (ex. foliar/topical application) nearing regulatory review. We report the development of the CEAS 300 population of Colorado potato beetle (Leptinotarsa decemlineata Say) (Coleoptera: Chrysomelidae) with > 11,100-fold resistance to a dsRNA targeting the V-ATPase subunit A gene after nine episodes of selection using non-transgenic delivery by foliar coating. Resistance was associated with lack of target gene down-regulation in CEAS 300 larvae and cross-resistance to another dsRNA target (COPI β; Coatomer subunit beta). In contrast, CEAS 300 larvae showed very low (~ 4-fold) reduced susceptibility to the Cry3Aa insecticidal protein from Bacillus thuringiensis. Resistance to dsRNA in CEAS 300 is transmitted as an autosomal recessive trait and is polygenic. These data represent the first documented case of resistance in an insect pest with high pesticide resistance potential using dsRNA delivered through non-transgenic techniques. Information on the genetics of resistance and availability of dsRNA-resistant L. decemlineata guide the design of resistance management tools and allow research to identify resistance alleles and estimate resistance risks.
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http://dx.doi.org/10.1038/s41598-021-85876-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7985369PMC
March 2021

Recent climate change is creating hotspots of butterfly increase and decline across North America.

Glob Chang Biol 2021 Jun 22;27(12):2702-2714. Epub 2021 Mar 22.

Department of Entomology, University of Georgia, Athens, GA, USA.

Some insect populations are experiencing dramatic declines, endangering the crucial ecosystem services they provide. Yet, other populations appear robust, highlighting the need to better define patterns and underlying drivers of recent change in insect numbers. We examined abundance and biodiversity trends for North American butterflies using a unique citizen-science dataset that has recorded observations of over 8 million butterflies across 456 species, 503 sites, nine ecoregions, and 26 years. Butterflies are a biodiverse group of pollinators, herbivores, and prey, making them useful bellwethers of environmental change. We found great heterogeneity in butterfly species' abundance trends, aggregating near zero, but with a tendency toward decline. There was strong spatial clustering, however, into regions of increase, decrease, or relative stasis. Recent precipitation and temperature appeared to largely drive these patterns, with butterflies generally declining at increasingly dry and hot sites but increasing at relatively wet or cool sites. In contrast, landscape and butterfly trait predictors had little influence, though abundance trends were slightly more positive around urban areas. Consistent with varying responses by different species, no overall directional change in butterfly species richness or evenness was detected. Overall, a mosaic of butterfly decay and rebound hotspots appeared to largely reflect geographic variability in climate drivers. Ongoing controversy about insect declines might dissipate with a shift in focus to the causes of heterogeneous responses among taxa and sites, with climate change emerging as a key suspect when pollinator communities are broadly impacted.
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http://dx.doi.org/10.1111/gcb.15582DOI Listing
June 2021

Insect-plant relationships predict the speed of insecticide adaptation.

Evol Appl 2021 Feb 27;14(2):290-296. Epub 2020 Aug 27.

Department of Entomology and Plant Pathology Auburn University Auburn AL USA.

Herbivorous insects must circumvent the chemical defenses of their host plants and, in cropping systems, must also circumvent synthetic insecticides. The pre-adaptation hypothesis posits that when herbivorous insects evolve resistance to insecticides, they co-opt adaptations against host plant defenses. Despite its intuitive appeal, few predictions of this hypothesis have been tested systematically. Here, with survival analysis of more than 17,000 herbivore-insecticide interactions, we show that resistance evolution tends to be faster when herbivorous insect diets are broad (but not too broad) and when insecticides and plant defensive chemicals are similar (but not too similar). These general relations suggest a complex interplay between macro-evolutionary contingencies and contemporary population genetic processes, and provide a predictive framework to forecast which pest species are most likely to develop resistance to particular insecticide chemistries.
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http://dx.doi.org/10.1111/eva.13089DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7896708PMC
February 2021

Alcohol dependence activates ventral tegmental area projections to central amygdala in male mice and rats.

Addict Biol 2021 Jul 16;26(4):e12990. Epub 2020 Dec 16.

Departments of Physiology, Louisiana State University Health Science Center, New Orleans, Louisiana, USA.

The neural adaptations that occur during the transition to alcohol dependence are not entirely understood but may include a gradual recruitment of brain stress circuitry by mesolimbic reward circuitry that is activated during early stages of alcohol use. Here, we focused on dopaminergic and nondopaminergic projections from the ventral tegmental area (VTA), important for mediating acute alcohol reinforcement, to the central nucleus of the amygdala (CeA), important for alcohol dependence-related negative affect and escalated alcohol drinking. The VTA projects directly to the CeA, but the functional relevance of this circuit is not fully established. Therefore, we combined retrograde and anterograde tracing, anatomical, and electrophysiological experiments in mice and rats to demonstrate that the CeA receives input from both dopaminergic and nondopaminergic projection neurons primarily from the lateral VTA. We then used slice electrophysiology and fos immunohistochemistry to test the effects of alcohol dependence on activity and activation profiles of CeA-projecting neurons in the VTA. Our data indicate that alcohol dependence activates midbrain projections to the central amygdala, suggesting that VTA projections may trigger plasticity in the CeA during the transition to alcohol dependence and that this circuit may be involved in mediating behavioral dysregulation associated with alcohol dependence.
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http://dx.doi.org/10.1111/adb.12990DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8206248PMC
July 2021

Host plants and shape the population genetics of sympatric herbivore populations.

Evol Appl 2020 Dec 12;13(10):2740-2753. Epub 2020 Sep 12.

Department of Entomology University of Georgia Athens GA USA.

Changing climate and land-use practices have the potential to bring previously isolated populations of pest insects into new sympatry. This heightens the need to better understand how differing patterns of host-plant association, and unique endosymbionts, serve to promote genetic isolation or integration. We addressed these factors in populations of potato psyllid, (Šulc), a generalist herbivore that vectors a bacterial pathogen ( Liberibacter solanacearum, causal pathogen of zebra chip disease) of potato ( L.). Genome-wide SNP data revealed two major genetic clusters-psyllids collected from potato crops were genetically similar to psyllids found on a common weed, spp., but dissimilar from those found on another common non-crop host, L. Most psyllids found on spp. and potato represented a single mitochondrial cytochrome oxidase I (COI) haplotype that has been suggested to not be native to the region, and whose arrival may have been concurrent with zebra chip disease first emerging. The putatively introduced COI haplotype usually co-occurred with endosymbiotic , while the putatively resident COI haplotype generally did not. Genetic intermediates between the two genetic populations of insects were rare, consistent with recent sympatry or reproductive isolation, although admixture patterns of apparent hybrids were consistent with introgression of genes from introduced into resident populations. Our results suggest that both host-plant associations and endosymbionts are shaping the population genetic structure of sympatric psyllid populations associated with different non-crop hosts. It is of future interest to explicitly examine vectorial capacity of the two populations and their potential hybrids, as population structure and hybridization might alter regional vector capacity and disease outbreaks.
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http://dx.doi.org/10.1111/eva.13079DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7691456PMC
December 2020

Low Genetic Variability in MEAM1 Populations within Farmscapes of Georgia, USA.

Insects 2020 Nov 26;11(12). Epub 2020 Nov 26.

Department of Entomology, University of Georgia, 1109 Experiment Street, Griffin, GA 30223, USA.

is a whitefly species complex comprising important phloem feeding insect pests and plant virus vectors of many agricultural crops. Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED) are the two most invasive members of the species complex worldwide. The diversity of agroecosystems invaded by could potentially influence their population structure, but this has not been assessed at a farmscape level. A farmscape in this study is defined as heterogenous habitat with crop and non-crop areas spanning ~8 square kilometers. In this study, mitochondrial COI gene (mtCOI) sequences and six microsatellite markers were used to examine the population structure of MEAM1 colonizing different plant species at a farmscape level in Georgia, United States. Thirty-five populations of adult whiteflies on row and vegetable crops and weeds across major agricultural regions of Georgia were collected from fifteen farmscapes. Based on morphological features and mtCOI sequences, five species/cryptic species of whiteflies ( MEAM1, MED, , , ) were found. Analysis of 102 mtCOI sequences revealed the presence of a single MEAM1 haplotype across farmscapes in Georgia. Population genetics analyses (AMOVA, PCA and STRUCTURE) of MEAM1 (microsatellite data) revealed only minimal genetic differences among collected populations within and among farmscapes. Overall, our results suggest that there is a high level of gene flow among MEAM1 populations among farmscapes in Georgia. Frequent whitefly population explosions driven by a single or a few major whitefly-suitable hosts planted on a wide spatial scale may be the key factor behind the persistence of a single panmictic population over Georgia's farmscapes. These population structuring effects are useful for delineating the spatial scale at which whiteflies must be managed and predicting the speed at which alleles associated with insecticide resistance might spread.
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http://dx.doi.org/10.3390/insects11120834DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7760769PMC
November 2020

Can Generalist Predators Control ?

Insects 2020 Nov 23;11(11). Epub 2020 Nov 23.

Department of Entomology, University of Georgia, 2360 Rainwater Road, Tifton, GA 31793, USA.

The whitefly, , has developed resistance to many insecticides, renewing interest in the biological control of this global pest. Generalist predators might contribute to whitefly suppression if they commonly occur in infested fields and generally complement rather than interfere with specialized natural enemies. Here, we review literature from the last 20 years, across US cropping systems, which considers the impacts of generalist predators on . Laboratory feeding trials and molecular gut content analysis suggest that at least 30 different generalist predator species willingly and/or regularly feed on these whiteflies. Nine of these predators appear to be particularly impactful, and a higher abundance of a few of these predator species has been shown to correlate with greater predation in the field. Predator species often occupy complementary feeding niches, which would be expected to strengthen biocontrol, although intraguild predation is also common and might be disruptive. Overall, our review suggests that a bio-diverse community of generalist predators commonly attacks , with the potential to exert substantial control in the field. The key challenge will be to develop reduced-spray plans so that generalist predators, and other more specialized natural enemies, are abundant enough that their biocontrol potential is realized.
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http://dx.doi.org/10.3390/insects11110823DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7700500PMC
November 2020

What Is the Spatial Extent of a Population?

Insects 2020 Nov 18;11(11). Epub 2020 Nov 18.

Department of Entomology, University of Georgia, Athens, GA 30602, USA.

Effective pest management depends on basic knowledge about insect dispersal patterns and gene flow in agroecosystems. The globally invasive sweet potato whitefly (Gennadius) (Hemiptera: Aleyrodidae) is considered a weak flier whose life history nonetheless predisposes it to frequent dispersal, but the scale over which populations exchange migrants, and should therefore be managed, is uncertain. In this review, we synthesize the emergent literature on population genetics to address the question: What spatial scales define populations? We find that within-species genetic differentiation among sites is often low, and evidence of population structuring by host plant or geography is rare. Heterozygote deficits prevail among populations, indicating that migrants from divergent populations are frequently sampled together. Overall, these results suggest that there is high ongoing gene flow over large spatial extents. However, genetic homogeneity typical of recently invading populations could obscure power to detect real isolation among populations. Genome-wide data collected systematically across space and time could distinguish signatures of invasion history from those of ongoing gene flow. Characterizing the spatial extent of populations could reveal whether insecticide rotations can be tailored to specific commodities or if coordination across linked commodities and regions is justified.
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http://dx.doi.org/10.3390/insects11110813DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7698913PMC
November 2020

Organic Farming Sharpens Plant Defenses in the Field.

Front Sustain Food Syst 2020 Jul 17;4. Epub 2020 Jul 17.

Department of Entomology, University of Georgia, Athens, GA, United States.

Plants deploy a variety of chemical and physical defenses to protect themselves against herbivores and pathogens. Organic farming seeks to enhance these responses by improving soil quality, ultimately altering bottom up regulation of plant defenses. While laboratory studies suggest this approach is effective, it remains unclear whether organic agriculture encourages more-active plant defenses under real-world conditions. Working on the farms of cooperating growers, we examined gene expression in the leaves of two potato () varieties, grown on organic vs. conventional farms. For one variety, , we found significantly heightened initiation of genes associated with plant-defense pathways in plants grown in organic vs. conventional fields. Organic fields exhibited lower levels of nitrate in soil and of nitrogen in plant foliage, alongside differences in communities of soil bacteria, suggesting possible links between soil management and observed differences in plant defenses. Additionally, numbers of predatory and phloem-feeding insects were higher in organic than conventional fields. A second potato variety, , which is generally grown using fewer inputs and in poorer-quality soils, exhibited lower overall herbivore and predator numbers, few differences in soil ecology, and no differences in gene-activity in organic and conventional farming systems. Altogether, our results suggest that organic farming has the potential to increase plants' resistance to herbivores, possibly facilitating reduced need for insecticide applications. These benefits appear to be mediated by plant variety and/or farming context.
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http://dx.doi.org/10.3389/fsufs.2020.00097DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7566882PMC
July 2020

No net insect abundance and diversity declines across US Long Term Ecological Research sites.

Nat Ecol Evol 2020 10 10;4(10):1368-1376. Epub 2020 Aug 10.

Department of Biology and Health Sciences, Hendrix College, Conway, AR, USA.

Recent reports of dramatic declines in insect abundance suggest grave consequences for global ecosystems and human society. Most evidence comes from Europe, however, leaving uncertainty about insect population trends worldwide. We used >5,300 time series for insects and other arthropods, collected over 4-36 years at monitoring sites representing 68 different natural and managed areas, to search for evidence of declines across the United States. Some taxa and sites showed decreases in abundance and diversity while others increased or were unchanged, yielding net abundance and biodiversity trends generally indistinguishable from zero. This lack of overall increase or decline was consistent across arthropod feeding groups and was similar for heavily disturbed versus relatively natural sites. The apparent robustness of US arthropod populations is reassuring. Yet, this result does not diminish the need for continued monitoring and could mask subtler changes in species composition that nonetheless endanger insect-provided ecosystem services.
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http://dx.doi.org/10.1038/s41559-020-1269-4DOI Listing
October 2020

A draft genome of a field-collected strain NW.

J Nematol 2020 ;52:1-7

Department of Entomology, Washington State University , Pullman, WA ; Current: Department of Entomology, University of Georgia , Athens, GA.

Advances in sequencing technologies have accelerated our understanding of the complex genetic network of organisms and genomic divergences that are linked to evolutionary processes. While many model organisms and laboratory strains have been sequenced, wild populations are underrepresented in the growing list of sequenced genomes. Here, we present a assembly of , strain NW, collected from a working agricultural field in south central Washington, USA. Leveraging Pacific Biosciences (PacBio) long reads, we sequenced strain NW to a high depth (99×). The resulting assembly is significantly larger than the previous assembly generated from the laboratory strain SN, with a noticeable improvement in continuity and completeness. Comparative analysis of two assemblies revealed numerous single nucleotide polymorphisms (SNPs), breakpoints, and indels present between the two genomes. This alternative genome resource and annotation could benefit the research community to examine the genetic foundation of evolutionary processes as well as genomic variation among conspecific populations.

Advances in sequencing technologies have accelerated our understanding of the complex genetic network of organisms and genomic divergences that are linked to evolutionary processes. While many model organisms and laboratory strains have been sequenced, wild populations are underrepresented in the growing list of sequenced genomes. Here, we present a assembly of , strain NW, collected from a working agricultural field in south central Washington, USA. Leveraging Pacific Biosciences (PacBio) long reads, we sequenced strain NW to a high depth (99×). The resulting assembly is significantly larger than the previous assembly generated from the laboratory strain SN, with a noticeable improvement in continuity and completeness. Comparative analysis of two assemblies revealed numerous single nucleotide polymorphisms (SNPs), breakpoints, and indels present between the two genomes. This alternative genome resource and annotation could benefit the research community to examine the genetic foundation of evolutionary processes as well as genomic variation among conspecific populations.
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http://dx.doi.org/10.21307/jofnem-2020-003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7265891PMC
January 2020

Landscape structure and climate drive population dynamics of an insect vector within intensely managed agroecosystems.

Ecol Appl 2020 07 23;30(5):e02109. Epub 2020 Mar 23.

Department of Entomology, Washington State University, Pullman, Washington, 99164, USA.

Characterizing factors affecting insect pest populations across variable landscapes is a major challenge for agriculture. In natural ecosystems, insect populations are strongly mediated by landscape and climatic factors. However, it has proven difficult to evaluate if similar factors predict pest dynamics in agroecosystems because control tactics exert strong confounding effects. We addressed this by assessing whether species distribution models could effectively characterize dynamics of an insect pest in intensely managed agroecosystems. Our study used a regional multi-year data set to assess landscape and climatic drivers of potato psyllid (Bactericera cockerelli) populations, which are often subjected to calendar-based insecticide treatments because they transmit pathogens to crops. Despite this, we show that psyllid populations were strongly affected by landscape and climatic factors. Psyllids were more abundant in landscapes with high connectivity, low crop diversity, and large natural areas. Psyllid population dynamics were also mediated by climatic factors, particularly precipitation and humidity. Our results show that many of the same factors that drive insect population dynamics in natural ecosystems can have similar effects in an intensive agroecosystem. More broadly, our study shows that models incorporating landscape and climatic factors can describe pest populations in agroecosystems and may thus promote more sustainable pest management.
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http://dx.doi.org/10.1002/eap.2109DOI Listing
July 2020

Are we overestimating risk of enteric pathogen spillover from wild birds to humans?

Biol Rev Camb Philos Soc 2020 06 31;95(3):652-679. Epub 2020 Jan 31.

Department of Entomology, Washington State University, 100 Dairy Road, P.O. Box 646382, Pullman, WA, 99164, U.S.A.

Enteric illnesses remain the second largest source of communicable diseases worldwide, and wild birds are suspected sources for human infection. This has led to efforts to reduce pathogen spillover through deterrence of wildlife and removal of wildlife habitat, particularly within farming systems, which can compromise conservation efforts and the ecosystem services wild birds provide. Further, Salmonella spp. are a significant cause of avian mortality, leading to additional conservation concerns. Despite numerous studies of enteric bacteria in wild birds and policies to discourage birds from food systems, we lack a comprehensive understanding of wild bird involvement in transmission of enteric bacteria to humans. Here, we propose a framework for understanding spillover of enteric pathogens from wild birds to humans, which includes pathogen acquisition, reservoir competence and bacterial shedding, contact with people and food, and pathogen survival in the environment. We place the literature into this framework to identify important knowledge gaps. Second, we conduct a meta-analysis of prevalence data for three human enteric pathogens, Campylobacter spp., E. coli, and Salmonella spp., in 431 North American breeding bird species. Our literature review revealed that only 3% of studies addressed the complete system of pathogen transmission. In our meta-analysis, we found a Campylobacter spp. prevalence of 27% across wild birds, while prevalence estimates of pathogenic E. coli (20%) and Salmonella spp. (6.4%) were lower. There was significant bias in which bird species have been tested, with most studies focusing on a small number of taxa that are common near people (e.g. European starlings Sturnus vulgaris and rock pigeons Columba livia) or commonly in contact with human waste (e.g. gulls). No pathogen prevalence data were available for 65% of North American breeding bird species, including many commonly in contact with humans (e.g. black-billed magpie Pica hudsonia and great blue heron Ardea herodias), and our metadata suggest that some under-studied species, taxonomic groups, and guilds may represent equivalent or greater risk to human infection than heavily studied species. We conclude that current data do not provide sufficient information to determine the likelihood of enteric pathogen spillover from wild birds to humans and thus preclude management solutions. The primary focus in the literature on pathogen prevalence likely overestimates the probability of enteric pathogen spillover from wild birds to humans because a pathogen must survive long enough at an infectious dose and be a strain that is able to colonize humans to cause infection. We propose that future research should focus on the large number of under-studied species commonly in contact with people and food production and demonstrate shedding of bacterial strains pathogenic to humans into the environment where people may contact them. Finally, studies assessing the duration and intensity of bacterial shedding and survival of bacteria in the environment in bird faeces will help provide crucial missing information necessary to calculate spillover probability. Addressing these essential knowledge gaps will support policy to reduce enteric pathogen spillover to humans and enhance bird conservation efforts that are currently undermined by unsupported fears of pathogen spillover from wild birds.
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http://dx.doi.org/10.1111/brv.12581DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7317827PMC
June 2020

Behavioural profiling of autism connectivity abnormalities.

BJPsych Open 2020 Jan 22;6(1):e11. Epub 2020 Jan 22.

Assistant Professor, Autism and Developmental Medicine Institute, Geisinger; and Department of Basic Sciences, Geisinger Commonwealth School of Medicine, USA.

Background: Brain regions are functionally diverse, and a given region may engage in a variety of tasks. This functional diversity of brain regions may be one factor that has prevented the finding of consistent biomarkers for brain disorders such as autism spectrum disorder (ASD). Thus, methods to characterise brain regions would help to determine how functional abnormalities contribute to affected behaviours.

Aims: As the first illustration of the meta-analytic behavioural profiling procedure, we evaluated how the regions with disrupted connectivity in ASD contributed to various behaviours.

Method: Connectivity abnormalities were determined from a published degree centrality group comparison based on functional magnetic resonance imaging data from the Autism Brain Imaging Data Exchange. Using BrainMap's database of task-based neuroimaging studies, behavioural profiles were created for abnormally connected regions by relating these regions to tasks activating them.

Results: Hyperconnectivity in ASD brains was significantly related to memory, attention, reasoning, social, execution and speech behaviours. Hypoconnectivity was related to vision, execution and speech behaviours.

Conclusions: The procedure outlines the first clinical neuroimaging application of a behavioural profiling method that estimates the functional diversity of brain regions, allowing for the relation of abnormal functional connectivity to diagnostic criteria. Behavioural profiling and the computational insights it provides can facilitate better understanding of the functional manifestations of various disorders, including ASD.
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http://dx.doi.org/10.1192/bjo.2019.102DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7001469PMC
January 2020

Biaxial Stress Relaxation of Vaginal Tissue in Pubertal Gilts.

J Biomech Eng 2020 03;142(3)

STRETCH Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA 24061.

Pelvic organ prolapse (POP) is a condition characterized by displacement of the vagina from its normal anatomical position leading to symptoms such as incontinence, physical discomfort, and poor self-image. Conservative treatment has shown limited success and surgical procedures, including the use of mesh, often lead to severe complications. To improve the current treatment methods for prolapse, the viscoelastic properties of vaginal tissue need to be characterized. We determined the biaxial stress relaxation response of vaginal tissue isolated from healthy pubertal gilts. Square specimens (n = 20) with sides aligned along the longitudinal directions (LD) and circumferential direction (CD) of the vagina were biaxially displaced up to 5 N. The specimens were then kept at the displacements corresponding to 5 N for 20 min in both the LD and CD, and the corresponding strains were measured using digital image correlation (DIC). The stresses in the LD and CD were found to decrease by 49.91 ± 5.81% and 46.22 ± 5.54% after 20 min, respectively. The strain in the LD and CD increased slightly from 0.080 ± 0.054 to 0.091 ± 0.064 and 0.050 ± 0.039 to 0.058 ± 0.047, respectively, but these changes were not significant (p > 0.01). By using the Peleg model, the initial decay rate and the asymptotic stress during stress relaxation were found to be significantly higher in the LD than in the CD (p≪0.001), suggesting higher stress relaxation in the LD. These findings may have implications for improving current surgical mesh, mechanical devices, and physical therapy used for prolapse treatment.
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http://dx.doi.org/10.1115/1.4045707DOI Listing
March 2020

Highly diversified crop-livestock farming systems reshape wild bird communities.

Ecol Appl 2020 03 2;30(2):e02031. Epub 2019 Dec 2.

Department of Entomology, Washington State University, Pullman, Washington, 99164 , USA.

Agricultural intensification is a leading threat to bird conservation. Highly diversified farming systems that integrate livestock and crop production might promote a diversity of habitats useful to native birds foraging across otherwise-simplified landscapes. At the same time, these features might be attractive to nonnative birds linked to a broad range of disservices to both crop and livestock production. We evaluated the influence of crop-livestock integration on wild bird richness and density along a north-south transect spanning the U.S. West Coast. We surveyed birds on 52 farms that grew primarily mixed vegetables and fruits alone or integrated livestock into production. Crop-livestock systems harbored higher native bird density and richness relative to crop-only farms, a benefit more pronounced on farms embedded in nonnatural landscapes. Crop-livestock systems bolstered native insectivores linked to the suppression of agricultural pest insects but did not bolster native granivores that may be more likely to damage crops. Crop-livestock systems also significantly increased the density of nonnative birds, primarily European Starlings (Sturnus vulgaris) and House Sparrows (Passer domesticus) that may compete with native birds for resources. Models supported a small, positive correlation between nonnative density and overall native bird density as well as between nonnative density and native granivore density. Relative to crop-only farms, on average, crop-livestock systems exhibited 1.5 times higher patch richness, 2.4 times higher density of farm structures, 7.3 times smaller field sizes, 2.4 times greater integration of woody crops, and 5.3 times greater integration of pasture/hay habitat on farm. Wild birds may have responded to this habitat diversity and/or associated food resources. Individual farm factors had significantly lower predictive power than farming system alone (change in C statistic information criterion (ΔCIC) = 80.2), suggesting crop-livestock systems may impact wild birds through a suite of factors that change with system conversion. Collectively, our findings suggest that farms that integrate livestock and crop production can attract robust native bird communities, especially within landscapes devoted to intensified food production. However, additional work is needed to demonstrate persistent farm bird communities through time, ecophysiological benefits to birds foraging on these farms, and net effects of both native and nonnative wild birds in agroecosystems.
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http://dx.doi.org/10.1002/eap.2031DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7078872PMC
March 2020

Organic Soils Control Beetle Survival While Competitors Limit Aphid Population Growth.

Environ Entomol 2019 12;48(6):1323-1330

Department of Entomology, Washington State University, Pullman, WA.

Soil chemistry and microbial diversity can impact the vigor and nutritive qualities of plants, as well as plants' ability to deploy anti-herbivore defenses. Soil qualities often vary dramatically on organic versus conventional farms, reflecting the many differences in soil management practices between these farming systems. We examined soil-mediated effects on herbivore performance by growing potato plants (Solanum tuberosum L.) in soils collected from organic or conventional commercial farm fields, and then exposing these plants to herbivory by green peach aphids (Myzus persicae Sulzer, Hemiptera: Aphididae) and/or Colorado potato beetles (Leptinotarsa decemlineata Say, Coleoptera: Chrysomelidae). Responses of the two potato pests varied dramatically. Survivorship of Colorado potato beetles was almost 3× higher on plants grown in organic than in conventional soils, but was unaffected by the presence of aphids. In contrast, aphid colony growth was twice as rapid when aphids were reared alone rather than with Colorado potato beetles, but was unaffected by soil type. We saw no obvious differences in soil nutrients when comparing organic and conventional soils. However, we saw a higher diversity of bacteria in organic soils, and potato plants grown in this soil had a lower carbon concentration in foliar tissue. In summary, the herbivore species differed in their susceptibility to soil- versus competitor-mediated effects, and these differences may be driven by microbe-mediated changes in host plant quality. Our results suggest that soil-mediated effects on pest growth can depend on herbivore species and community composition, and that soil management strategies that promote plant health may also increase host quality for pests.
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http://dx.doi.org/10.1093/ee/nvz100DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6885743PMC
December 2019

An evaluation of automated tracing for orbitofrontal cortex sulcogyral pattern typing.

J Neurosci Methods 2019 10 1;326:108386. Epub 2019 Aug 1.

Geisinger-Bucknell Autism & Developmental Medicine Institute, Lewisburg, PA United States. Electronic address:

Background: Characterization of stereotyped orbitofrontal cortex (OFC) sulcogyral patterns formed by the medial and lateral orbitofrontal sulci (MOS and LOS) can be used to characterize individual variability; however, in practice, issues exist for reliability and reproducibility of anatomical classifications, as current methods rely on manual tracing.

New Method: We assessed whether an automated tracing procedure would be useful for characterizing OFC sulcogyral patterns. 100 subjects from a published collection of manual OFC tracings and characterizations of patients with bipolar disorder, schizophrenia, and typical controls were used to evaluate an automated tracing procedure implemented using the BrainVISA Morphologist Pipeline.

Results: Automated tracings of caudal and rostral segments of the medial (MOSc/MOSr) and lateral (LOSc/LOSr) orbitofrontal sulci, as well as the intermediate (IOS) and transverse orbitofrontal sulci (TOS) were found to accurately identify OFC sulci, accurately portray sulci continuity, and reliably inform manual sulcogyral pattern characterization.

Comparison With Existing Method: Automated tracings produced visibly similar tracings of OFC sulci and removed subjective influence from locating sulci. The semi-automated pipeline of automated tracing and manual sulcogyral pattern characterization can eliminate the need for direct input during the most time-consuming process of the manual pipeline.

Conclusions: The results suggest that automated OFC sulci tracing methods using BrainVISA Morphologist are feasible and useful in a semi-automated pipeline to characterize OFC sulcogyral patterns. Automated OFC sulci tracing methods will improve reliability and reproducibility of sulcogyral characterizations and can allow for characterizations of sulcal patterns types in larger sample sizes, previously unattainable using traditional manual tracing procedures.
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http://dx.doi.org/10.1016/j.jneumeth.2019.108386DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8050840PMC
October 2019

A sticky situation: honeydew of the pear psylla disrupts feeding by its predator Orius sauteri.

Pest Manag Sci 2020 Jan 8;76(1):75-84. Epub 2019 Jul 8.

Department of Entomology, China Agricultural University, Beijing, China.

Background: Honeydew is valuable food source for predators that can build predator numbers and strengthen biological control. Honeydew excreted by hemipterans often supplements the diets of their predators and parasitoids. However, dense sticky honeydew also creates a difficult foraging environment, potentially limiting predator efficiency.

Results: We examined the benefits and costs of honeydew excreted by the pear psylla (Cacopsylla chinensis [Yang and Li]) for its key predator in much of Asia, the anthocorid bug Orius sauteri (Poppius). We found these predators spent more time foraging and laid more eggs in the presence of psyllid honeydew compared to the control. However, predators more often foraged among psylla without honeydew than those coated in honeydew. This suggests that while O. sauteri recognized honeydew as a useful cue to prey presence, the predators were more likely to attack pear psylla lacking the sugary excretion. In foraging trials, honeydew consistently reduced the number of psyllids killed by the predator, suggesting it limited O. sauteri mobility or reduced the nutritional value of psyllids as prey. We also found slowed development, reduced longevity, and reduced fecundity of O. sauteri reared on moth eggs (Sitotroga cerealella [Olivier]) coated in honeydew compared to those reared on moth eggs alone.

Conclusion: Altogether, our results suggest that psyllid honeydew could serve as a prey-location and oviposition cue for O. sauteri. However, honeydew also limited predator foraging with the potential to limit biological control. More generally, honeydew might form an important type of defense for stationary feeders like psyllids. © 2019 Society of Chemical Industry.
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http://dx.doi.org/10.1002/ps.5498DOI Listing
January 2020

Bacteria and Competing Herbivores Weaken Top-Down and Bottom-Up Aphid Suppression.

Front Plant Sci 2018 3;9:1239. Epub 2018 Sep 3.

Department of Entomology, Washington State University, Pullman, WA, United States.

Herbivore suppression is mediated by both plant defenses and predators. In turn, plant defenses are impacted by soil fertility and interactions with soil bacteria. Measuring the relative importance of nutritional and microbial drivers of herbivore resistance has proven problematic, in part because it is difficult to manipulate soil-bacterial community composition. Here, we exploit variation in soil fertility and microbial biodiversity across 20 farms to untangle suppression of aphids () through bottom-up and top-down channels. We planted plants in soil from each farm, manipulated single and dual infestations of aphids alone or with caterpillars (), and exposed aphids to parasitoid wasps () in the open field. We then used multi-model inference to identify the strongest soil-based predictors of herbivore growth and parasitism. We found that densities of spp., a genus known to include plant-growth-promoting rhizobacteria, negatively correlated with aphid suppression by specialist parasitoids. Aphid parasitism also was disrupted on plants that had caterpillar damage, compared to plants attacked only by aphids. Relative abundance of spp. bacteria correlated with higher aphid growth, although this appeared to be a direct effect, as aphid parasitism was not associated with this group of bacteria. Non-pathogenic soil bacteria are often shown to deliver benefits to plants, improving plant nutrition and the deployment of anti-herbivore defenses. However, our results suggest that these plant growth-promoting bacteria may also indirectly weaken top-down aphid suppression by parasitoids and directly improve aphid performance. Against a background of varying soil fertility, microbial biodiversity, competing herbivores, and natural enemies, we found that effects of non-pathogenic soil microbes on aphid growth outweighed those of nutritional factors. Therefore, predictions about the strength of plant defenses along resource gradients must be expanded to include microbial associates.
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http://dx.doi.org/10.3389/fpls.2018.01239DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6129616PMC
September 2018

Dung beetle-mediated soil modification: a data set for analyzing the effects of a recent introduction on soil quality.

Ecology 2018 07 12;99(7):1694. Epub 2018 Jun 12.

Department of Entomology, Washington State University, Pullman, Washington, 99164, USA.

Globally, dung beetles (Scarabaeidae: Scarabaeinae) are linked to many critical ecosystem processes involving the consumption and breakdown of mammal dung. Due to New Zealand's unique evolutionary history, resulting from its geographic isolation from Gondwana, endemic dung-dwelling fauna evolved in the absence of large mammals. Europeans introduced livestock to the islands in the late 18th and 19th centuries, resulting in a buildup of undecomposed feces and unrecycled nutrients due to the absence of dung beetles. To mitigate this situation, in 2011, the New Zealand Environmental Protection Agency approved the release of 11 species of exotic beetles with the expectation that these insects would fulfill a critically missing link in converting aboveground manure biomass into higher quality soils belowground. Widespread releases began in 2014. To enable others in the future to test the environmental impacts of the beetle introductions, we present a detailed characterization of soil physical, chemical, and biological properties, shortly after the initial and intentional introduction of dung beetles to 16 release sites across both the North and South Islands of New Zealand. As beetle populations become established, these baseline data will enable quantification of the degree to which different exotic dung beetle communities can modify soils, specifically if they facilitate soil nutrient cycling. There are no copyright or proprietary restrictions for research or teaching purposes. Usage of the data set must be cited by referencing this publication.
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http://dx.doi.org/10.1002/ecy.2374DOI Listing
July 2018

Monitoring frequency of intra-fraction patient motion using the ExacTrac system for LINAC-based SRS treatments.

J Appl Clin Med Phys 2018 May 25;19(3):58-63. Epub 2018 Mar 25.

Department of Radiation Oncology, Virginia Commonwealth University, Richmond, VA, USA.

Purpose: The aim of this study was to investigate the intra-fractional patient motion using the ExacTrac system in LINAC-based stereotactic radiosurgery (SRS).

Method: A retrospective analysis of 104 SRS patients with kilovoltage image-guided setup (Brainlab ExacTrac) data was performed. Each patient was imaged pre-treatment, and at two time points during treatment (1st and 2nd mid-treatment), and bony anatomy of the skull was used to establish setup error at each time point. The datasets included the translational and rotational setup error, as well as the time period between image acquisitions. After each image acquisition, the patient was repositioned using the calculated shift to correct the setup error. Only translational errors were corrected due to the absence of a 6D treatment table. Setup time and directional shift values were analyzed to determine correlation between shift magnitudes as well as time between acquisitions.

Results: The average magnitude translation was 0.64 ± 0.59 mm, 0.79 ± 0.45 mm, and 0.65 ± 0.35 mm for the pre-treatment, 1st mid-treatment, and 2nd mid-treatment imaging time points. The average time from pre-treatment image acquisition to 1st mid-treatment image acquisition was 7.98 ± 0.45 min, from 1st to 2nd mid-treatment image was 4.87 ± 1.96 min. The greatest translation was 3.64 mm, occurring in the pre-treatment image. No patient had a 1st or 2nd mid-treatment image with greater than 2 mm magnitude shifts.

Conclusion: There was no correlation between patient motion over time, in direction or magnitude, and duration of treatment. The imaging frequency could be reduced to decrease imaging dose and treatment time without significant changes in patient position.
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http://dx.doi.org/10.1002/acm2.12279DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5978384PMC
May 2018

Dual-guild herbivory disrupts predator-prey interactions in the field.

Ecology 2018 05;99(5):1089-1098

Department of Entomology, Washington State University, Pullman, Washington, 99164, USA.

Plant defenses often mediate whether competing chewing and sucking herbivores indirectly benefit or harm one another. Dual-guild herbivory also can muddle plant signals used by specialist natural enemies to locate prey, further complicating the net impact of herbivore-herbivore interactions in naturally diverse settings. While dual-guild herbivore communities are common in nature, consequences for top-down processes are unclear, as chemically mediated tri-trophic interactions are rarely evaluated in field environments. Combining observational and experimental approaches in the open field, we test a prediction that chewing herbivores interfere with top-down suppression of phloem feeders on Brassica oleracea across broad landscapes. In a two-year survey of 52 working farm sites, we found that parasitoid and aphid densities on broccoli plants positively correlated at farms where aphids and caterpillars rarely co-occurred, but this relationship disappeared at farms where caterpillars commonly co-occurred. In a follow-up experiment, we compared single and dual-guild herbivore communities at four local farm sites and found that caterpillars (P. rapae) caused a 30% reduction in aphid parasitism (primarily by Diaeretiella rapae), and increased aphid colony (Brevicoryne brassicae) growth at some sites. Notably, in the absence of predators, caterpillars indirectly suppressed, rather than enhanced, aphid growth. Amid considerable ecological noise, our study reveals a pattern of apparent commensalism: herbivore-herbivore facilitation via relaxed top-down suppression. This work suggests that enemy-mediated apparent commensalism may override constraints to growth induced by competing herbivores in field environments, and emphasizes the value of placing chemically mediated interactions within their broader environmental and community contexts.
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http://dx.doi.org/10.1002/ecy.2192DOI Listing
May 2018

Native turncoats and indirect facilitation of species invasions.

Proc Biol Sci 2018 01;285(1871)

Centre for Tropical, Environmental, and Sustainability Sciences, College of Science and Engineering, James Cook University, Cairns, Australia.

At local scales, native species can resist invasion by feeding on and competing with would-be invasive species. However, this relationship tends to break down or reverse at larger scales. Here, we consider the role of native species as indirect facilitators of invasion and their potential role in this diversity-driven 'invasion paradox'. We coin the term 'native turncoats' to describe native facilitators of non-native species and identify eight ways they may indirectly facilitate species invasion. Some are commonly documented, while others, such as indirect interactions within competitive communities, are largely undocumented in an invasion context. Therefore, we use models to evaluate the likelihood that these competitive interactions influence invasions. We find that native turncoat effects increase with the number of resources and native species. Furthermore, our findings suggest the existence, abundance and effectiveness of native turncoats in a community could greatly influence invasion success at large scales.
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http://dx.doi.org/10.1098/rspb.2017.1936DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5805925PMC
January 2018
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