bluuebunny/crossref_metadata_2025_split huggingface dataset:
Old divergence and restricted gene flow between torrent duck (Merganetta armata) subspecies in the Central and Southern Andes
Authors: Alza Luis , Lavretsky Philip , Peters Jeffrey L. , Cerón Gerardo , Smith Matthew , Kopuchian Cecilia , Astie Andrea , McCracken Kevin G. 
Published: August 2019

AbstractAimTo investigate the structure and rate of gene flow among populations of habitat‐specialized species to understand the ecological and evolutionary processes underpinning their population dynamics and historical demography, including speciation and extinction.LocationPeruvian and Argentine Andes.TaxonTwo subspecies of torrent duck (Merganetta armata).MethodsWe sampled 156 individuals in Peru (M. a. leucogenis; Chillón River, n = 57 and Pachachaca River, n = 49) and Argentina (M. a. armata; Arroyo Grande River, n = 33 and Malargüe River, n = 17), and sequenced the mitochondrial DNA (mtDNA) control region to conduct coarse and fine‐scale demographic analyses of population structure. Additionally, to test for differences between subspecies, and across genetic markers with distinct inheritance patterns, a subset of individuals (Peru, n = 10 and Argentina, n = 9) was subjected to partial genome resequencing, obtaining 4,027 autosomal and 189 Z‐linked double‐digest restriction‐associated DNA sequences.ResultsHaplotype and nucleotide diversities were higher in Peru than Argentina across all markers. Peruvian and Argentine subspecies showed concordant species‐level differences (ΦST mtDNA = 0.82; ΦST autosomal = 0.30; ΦST Z chromosome = 0.45), including no shared mtDNA haplotypes. Demographic parameters estimated for mtDNA using IM and IMa2 analyses, and for autosomal markers using ∂a∂i (isolation‐with‐migration model), supported an old divergence (mtDNA = 600,000 years before present (ybp), 95% HPD range = 1.2 Mya to 200,000 ybp; and autosomal ∂a∂i = 782,490 ybp), between the two subspecies, characteristic of deeply diverged lineages. The populations were well‐differentiated in Argentina but moderately differentiated in Peru, with low unidirectional gene flow in each country.Main conclusionsWe suggest that the South American Arid Diagonal was preexisting and remains a current phylogeographic barrier between the ranges of the two torrent duck subspecies, and the adult territoriality and breeding site fidelity to the rivers define their population structure.
Divergence in drought‐response traits between sympatric species of Mimulus
Authors: Mantel Samuel J. , Sweigart Andrea L. 
Published: August 2019

AbstractDifferential adaptation to local environmental conditions is thought to be an important driver of speciation. Plants, whose sedentary lifestyle necessitates fine‐tuned adaptation to edaphic conditions such as water availability, are often distributed based on these conditions. Populations occupying water‐limited habitats may employ a variety of strategies, involving numerous phenotypes, to prevent and withstand desiccation. In sympatry, two closely related Mimulus species—M. guttatus and M. nasutus—occupy distinct microhabitats that differ in seasonal water availability. In a common garden experiment, we characterized natural variation within and between sympatric M. guttatus and M. nasutus in the ability to successfully set seed under well‐watered and drought conditions. We also measured key phenotypes for drought adaptation, including developmental timing, plant size, flower size, and stomatal density. Consistent with their microhabitat associations in nature, M. nasutus set seed much more successfully than M. guttatus under water‐limited conditions. This divergence in reproductive output under drought was due to differences in mortality after the onset of flowering, with M. nasutus surviving at a much higher rate than M. guttatus. Higher seed set in M. nasutus was mediated, at least in part, by a plastic increase in the rate of late‐stage development (i.e., fruit maturation), consistent with the ability of this species to inhabit more ephemeral habitats in the field. Our results suggest adaptation to water availability may be an important factor in species maintenance of these Mimulus taxa in sympatry.
Effects of extreme drought and wet events for tree mortality: Insights from tree‐ring width and carbon isotope ratio in a Siberian larch forest
Authors: Tei Shunsuke , Sugimoto Atsuko , Yonenobu Hitoshi , Kotani Ayumi , Maximov Trofim C. 
Published: August 2019

AbstractRecent studies suggest that forest vulnerability to tree mortality has increased as a result of extreme climate events such as severe drought and heavy rain. However, little is known about the mortality processes, particularly when they are induced by heavy rain. A dendroecological analysis was conducted on living and dead trees in a Siberian larch forest using the chronologies of 30 years of radial growth and carbon isotope (Δ13C) discrimination. The analysis demonstrates the relationship between heavy rain and larch tree mortality. Radial growth and Δ13C patterns in dead trees at a wet subsite diverged from those of living trees only during the heavy rain period in 2005–2007. On the other hand, the radial growth and Δ13C patterns in dead trees at the dry subsite diverged from those of living trees after severe drought events in 1998 and in 2002–2003. At the wet subsite, the heavy rain was intense enough to push the larch trees past their mortality threshold, whereas previous drought conditions also contributed to tree mortality at the dry subsite. Our results demonstrated that the process of larch tree mortality differs with site‐specific topographical soil moisture conditions, even when synchronous tree death occurs in a specific year of climatic extremes.
Improved root turnover assessment using field scanning rhizotrons with branch order analysis
Authors: Huo Changfu , Cheng Weixin 
Published: August 2019

AbstractRoot turnover is a key process contributing to soil carbon storage, nutrient cycling, and other ecosystem functions. However, quantifying root turnover rates remains highly uncertain and methodologically challenging. Field rhizotrons were employed to quantify root turnover times using median longevities of five branching orders in a Larix gmelinii plantation. Root images were recorded by scanning the rhizotron windows at a monthly interval during four growing seasons. Root demographic data and branching orders were obtained by analyzing these images using Rootfly software coupled with manual mouse‐tracing of individual roots. Root longevities and turnover estimates were calculated using these data. Roots of different branching orders showed significantly different turnover times. The mean turnover times of the first‐order roots and second‐order roots were 284 and 994 d, respectively. Roots of higher branching orders (third to fifth orders) remained alive at the end of the 4‐yr experimental period, indicating much longer turnover times than the duration of the experiment. Root turnover times increased exponentially with branching orders. Further analysis of these data suggested that root branching orders combined with sampling biases, timing of root cohorts, and longevity distribution patterns crucially influenced root turnover times. The method of combining field glass rhizotrons with electronic scanning permits quantification of root turnover for five branching orders in a temperate forest. The overall result empirically demonstrates the crucial role of branching orders for accurately quantifying root turnover times.
Accounting for aboveground carbon storage in shrubland and woodland ecosystems in the Great Basin
Authors: Fusco Emily J. , Rau Benjamin M. , Falkowski Michael , Filippelli Steven , Bradley Bethany A. 
Published: August 2019

AbstractImproving the accuracy of carbon accounting in terrestrial ecosystems is critical for understanding carbon fluxes associated with land cover change, with significant implications for global carbon cycling and climate change. Semi‐arid ecosystems account for an estimated 45% of global terrestrial ecosystem area and are in many locations experiencing high degrees of degradation. However, aboveground carbon accounting has largely focused on tropical and forested ecosystems, while drylands have been relatively neglected. Here, we used a combination of field estimates, remotely sensed data, and existing land cover maps to create a spatially explicit estimate of aboveground carbon storage within the Great Basin, a semi‐arid region of the western United States encompassing 643,500 km2 of shrubland and woodland vegetation. We classified the region into seven distinct land cover categories: pinyon‐juniper woodland, sagebrush steppe, salt desert shrub, low sagebrush, forest, non‐forest, and other/excluded, each with an associated carbon estimate. Aboveground carbon estimates for pinyon‐juniper woodland were continuous values based on tree canopy cover. Carbon estimates for other land cover categories were based on a mean value for the land cover type. The Great Basin ecosystems contain an estimated 295.4 Tg in aboveground carbon, which is almost double the previous estimates that only accounted for forested ecosystems in the same area. Aboveground carbon was disproportionately stored in pinyon‐juniper woodland (43.7% carbon, 16.9% land area), while the shrubland systems accounted for roughly half of the total land area (49.1%) and one‐third of the total carbon. Our results emphasize the importance of distinguishing and accounting for the distinctive contributions of shrubland and woodland ecosystems when creating carbon storage estimates for dryland regions.
Enhanced lipid production by Rhodotorula glutinis CGMCC 2.703 using a two‐stage pH regulation strategy with acetate as the substrate
Authors: Zhang Wen , Wu Jing , Zhou Yu‐Jie , Liu Hong‐Juan , Zhang Jian‐An 
Published: August 2019

AbstractIn recent years, VFAs as a novel, inexpensive substrate for biodiesel production have become a hot research topic. The effect of pH on lipid production by Rhodotorula glutinis when using acetate as a substrate was studied. The optimized initial acetate concentration and C/N ratio were 23 g/L and 350, respectively. In 1‐L bioreactors containing an initial acetate concentration of 23 g/L, the most suitable pH for cell growth was 6.6, while pH 7.0 was found optimal for lipid production. In the pH‐stat fed‐batch fermentation, an increased biomass yield of 67.2 g/L was obtained at pH 6.6, while an increased lipid titer of 29.3 g/L was obtained at pH 7.0. When using a two‐stage pH regulation culture strategy, the biomass yield, lipid titer, and lipid content reached 68.2 g/L, 35.8 g/L, and 52.5%, respectively. Both the biomass yield and lipid production were obviously enhanced. Compared with the batch culture, the biomass yield, lipid titer, and lipid content were increased 15.6‐fold, 19.1‐fold, and 21.0%, respectively, by using the two‐stage pH regulation culture strategy. The composition of the main fatty acids was compared when acetate or glucose was used as the substrate. The composition of the lipids produced using both substrates was similar to that of palm oil, indicating that lipids produced by R. glutinis in the presence of acetate showed promise for use as a biodiesel feedstock.
Porcine placental extract facilitates memory and learning in aged mice
Authors: Yamauchi Akihiro , Tone Takahiro , Sugimoto Koji , Seok Lim Hong , Kaku Taiichi , Tohda Chihiro , Shindo Takayuki , Tamada Koji , Mizukami Yoichi , Hirano Eiichi 
Published: August 2019

AbstractAging induces a decline in both memory and learning ability without predisposing an individual to diseases of the central nervous system, such as dementia. This decline can have a variety of adverse effects on daily life, and it can also gradually affect the individual and the people they are surrounded by. Since recent evidence indicated that placental extract has effects on brain function such as memory, we hypothesized that placental extract could ameliorate the age‐associated reduction in cognitive function in aging. Here, we investigated the effect of new modified porcine placental extract (SD‐F) on memory ability in aged mice at both the behavioral and molecular levels. Our results revealed that SD‐F significantly enhanced memory ability in the object recognition and object location tasks in a dose‐dependent manner in aged mice relative to controls. The numbers of Nissl‐positive cells in the hippocampal cornu ammonis 3 (CA3) and dentate gyrus (DG) regions were increased in SD‐F‐treated aged mice relative to controls. RNA‐seq analysis of the hippocampus of aged mice identified 542 differentially expressed genes, of which 216 were up‐regulated and 326 were down‐regulated in SD‐F‐treated mice relative to controls. Of the 216 up‐regulated genes, we identified four characteristic genes directly related to memory, including early growth response protein 1 (Egr1), growth arrest and DNA‐damage‐inducible, beta (Gadd45b), NGFI‐A binding protein 2 (Nab2), and vascular endothelial growth factor a (Vegfa). These results suggest that the efficacy of SD‐F involves upregulation of these genes.
Headquarters‐subsidiary knowledge strategies at the cluster level
Authors: Li Pengfei , Bathelt Harald 
Published: August 2019

AbstractResearch SummaryThis article examines how multinational enterprises (MNEs) leverage knowledge across clusters. Based on the geographical sources and the contextuality of knowledge, we construct a typology of four MNE knowledge strategies across space: replicating, scouting, connecting, and integrating, and take into consideration their spatial, industrial, and leadership contexts. A fuzzy‐set qualitative comparative analysis of 49 pairs of headquarters‐subsidiary linkages between Canada and China suggests that replicating strategies occur in cluster‐to‐non‐cluster contexts or in fields with a knowledge gap between the two countries, whereas scouting strategies are typical in non‐cluster‐to‐cluster investments. Connecting and integrating strategies are focused on cluster‐to‐cluster contexts. We also find that while connecting occurs in fields where knowledge is locally bounded, integrating takes place in nonlocally bounded contexts. Finally, scouting and integrating strategies are associated with home nationals as subsidiary leaders.Managerial SummaryHow do multinational enterprises (MNEs) transfer knowledge over space between clusters and between other locations? To explore this question, we construct a typology of four MNE knowledge strategies (replicating, scouting, connecting, and integrating) and examine the spatial, industrial, and leadership conditions of each. By examining 49 headquarter‐subsidiary linkages between Canada and China through detailed interviews, we find that replicating strategies occur in cluster‐to‐non‐cluster contexts or industries with a knowledge gap between the two countries, whereas scouting strategies are typical in non‐cluster‐to‐cluster investments. Connecting and integrating strategies are focused on cluster‐to‐cluster contexts. We also find that while connecting occurs in fields where knowledge is locally bounded, integrating dominates where this is not the case. Finally, scouting and integrating strategies are associated with home nationals as subsidiary leaders.
Serious immune‐related adverse events in patients with head and neck cancer after checkpoint blockade: Systematic review
Authors: Shah Mohsin , Jomaa Mona K. , Ferrarotto Renata , Yeung Sai‐Ching J. , Hanna Ehab Y. , Reyes‐Gibby Cielito C. 
Published: August 2019

AbstractBackgroundImmune checkpoint inhibitors confer significant clinical benefit by bolstering immune‐system activity, however, they also produce a spectrum of immune‐related adverse events (irAEs). Rapid recognition and timely treatment of these patients is essential for improved outcomes.MethodsWe conducted a systematic review of English‐language articles in MEDLINE, EMBASE, Web of Science, PubMed, and Cochrane CENTRAL databases on patients with head and neck cancer treated with immune checkpoint inhibitors who developed treatment‐related adverse events.ResultsOf 1715 unique citations, 11 studies met inclusion criteria. Eight patients with serious irAEs were reported from case reports and case series. Overall, 46 treatment‐related AEs were identified from the pooled 791 patients with at least 12 having potential relevance to irAEs. The most frequent AEs observed in patients receiving PD‐1 inhibitors involved the endocrine, cutaneous, and gastrointestinal systems.ConclusionsCharacterizing irAEs in longitudinal studies is needed for developing strategies for their prompt recognition and management.
Retro‐Corey‐Chaykovsky Epoxidation: Converting Geminal Disubstituted Epoxides to Ketones
Authors: Li Siqi , Li Pingfan , Xu Jiaxi 
Published: August 2019

AbstractCorey‐Chaykovsky epoxidation has been widely applied in the conversion of aldehydes and ketones to epoxides with sulfonium and sulfoxonium ylides. The reverse transformation is realized for conversion of geminal disubstituted epoxides to ketones in the presence of DABCO in refluxing mesitylene. The method is a weak basic transformation from epoxides to ketones with loss of a methylene group and can be applied as an alternative strategy of the acid‐catalyzed Meinwald rearrangement or oxidation for conversion of epoxides to carbonyl compounds.
Maternal depression and infant attachment security: A meta‐analysis
Authors: Barnes Jennifer , Theule Jennifer 
Published: August 2019

ABSTRACTThe purpose of this study is to clarify the magnitude of the association between maternal depression and infant attachment nonsecurity, and to identify possible moderators of this relationship. An extensive literature search was conducted using multiple databases of both published and unpublished studies. A meta‐analysis was conducted to determine the relationship between maternal depression and infant attachment security and to establish the effect size. The main findings from this meta‐analysis, which included 42 studies, indicate that there is a small, yet significant, relationship between maternal depression and infant attachment nonsecurity. The rate of nonsecurity in infants of mothers with depression was approximately 20% higher than expected rates in a nonclinical population, and the association between depressive symptoms and nonsecurity was small, but significant. Infants of mothers with depression were nearly twice as likely to have a nonsecure attachment than were infants of healthy mothers. Depression measure and maternal sample source were identified as significant moderators of the odds ratio effect size. Results of this study demonstrate that there is a significant relationship between maternal depression and infant attachment nonsecurity, and suggest that interventions that focus on both maternal mental health and the attachment relationship are warranted.
A machine perspective of atomic defects in scanning transmission electron microscopy
Authors: Dan Jiadong , Zhao Xiaoxu , Pennycook Stephen J. 
Published: August 2019

AbstractEnabled by the advances in aberration‐corrected scanning transmission electron microscopy (STEM), atomic‐resolution real space imaging of materials has allowed a direct structure‐property investigation. Traditional ways of quantitative data analysis suffer from low yield and poor accuracy. New ideas in the field of computer vision and machine learning have provided more momentum to harness the wealth of big data and sophisticated information in STEM data analytics, which has transformed STEM from a localized characterization technique to a macroscopic tool with intelligence. In this review article, we discuss the prime significance of defect topology and density in two‐dimensional (2D) materials, which have proved to be a powerful means to tune a wide range of properties. Subsequently, we systematically review advanced data analysis methods that have demonstrated promising prospects in analyzing STEM data, particularly for identifying structural defects, with high throughput and veracity. A unified framework for atomic structure identification is also summarized.
Chemoresistive materials for electronic nose: Progress, perspectives, and challenges
Authors: Park Seo Yun , Kim Yeonhoo , Kim Taehoon , Eom Tae Hoon , Kim Soo Young , Jang Ho Won 
Published: August 2019

AbstractAn electronic nose (e‐nose) is a device that can detect and recognize odors and flavors using a sensor array. It has received considerable interest in the past decade because it is required in several areas such as health care, environmental monitoring, industrial applications, automobile, food storage, and military. However, there are still obstacles in developing a portable e‐nose that can be used for a wide variety of applications. For practical applications of an e‐nose, it is necessary to collect a massive amount of data from various sensing materials that can transduce interactions with molecules reliably and analyze them via pattern recognition. In addition, the possibility of miniaturizing the e‐nose and operating it with low power consumption should be considered. Moreover, it should work efficiently over a long period of time. To satisfy these requirements, several different chemoresistive material platforms including metal oxides, organics such as polymers and carbon‐based materials, and two‐dimensional materials were investigated as sensor elements for an e‐nose. As an individual material has limited selectivity, there is a continuing effort to improve the selectivity and gas sensing properties through surface decoration and compositional and structural variations. To produce a reliable e‐nose, which can be used for practical applications, researches in various fields have to be harmonized. This paper reviews the progress of research on e‐noses based on a chemoresistive gas sensor array and discusses the inherent challenges and potential solutions.
Metal halide perovskite nanocrystals and their applications in optoelectronic devices
Authors: Lu Po , Lu Min , Wang Hua , Sui Ning , Shi Zhifeng , Yu William W. , Zhang Yu 
Published: August 2019

AbstractIn recent years, metal halide perovskite nanocrystals (NCs) have been favored by many researchers due to their unique properties including long carrier diffusion length, high carrier mobility, tunable emission wavelength, and narrow full width at half maximum, making them great application potentials in optoelectronic devices. The photoluminescence quantum yields of perovskite NCs are nearly 100%, and the device efficiency of perovskite NC‐based light‐emitting diodes (LEDs) has been improved significantly from below 0.1% to over 20%. In addition, perovskite NC‐based solar cells and photodetectors have also developed rapidly in recent years. Here, we summarize the synthesis and the basic optoelectronic properties of metal halide perovskite NCs and introduce their applications in LEDs, solar cells, and photodetectors.