bluuebunny/crossref_metadata_2025 huggingface dataset:
Matroid connectivity and singularities of configuration hypersurfaces
Authors: Denham Graham , Schulze Mathias , Walther Uli
Published: January 2021

Consider a linear realization of a matroid over a field. One associates with it a configuration polynomial and a symmetric bilinear form with linear homogeneous coefficients. The corresponding configuration hypersurface and its non-smooth locus support the respective first and second degeneracy scheme of the bilinear form. We show that these schemes are reduced and describe the effect of matroid connectivity: for (2-)connected matroids, the configuration hypersurface is integral, and the second degeneracy scheme is reduced Cohen–Macaulay of codimension 3. If the matroid is 3-connected, then also the second degeneracy scheme is integral. In the process, we describe the behavior of configuration polynomials, forms and schemes with respect to various matroid constructions.
Flavonoids improve drought tolerance of maize seedlings by regulating the homeostasis of reactive oxygen species
Authors: Li Baozhu , Fan Ruonan , Sun Guiling , Sun Ting , Fan Yanting , Bai Shenglong , Guo Siyi , Huang Shiquan , Liu Jiong , Zhang Hui , Wang Pengtao , Zhu Xiaohong , Song Chun-peng
Published: January 2021

Background and aims

As drought threatens the yield and quality of maize (Zea mays L.), it is important to dissect the molecular basis of maize drought tolerance. Flavonoids, participate in the scavenging of oxygen free radicals and alleviate stress-induced oxidative damages. This study aims to dissect the function of flavonoids in the improvement of maize drought tolerance.

Methods

Using far-infrared imaging screening, we previously isolated a drought overly insensitivity (doi) mutant from an ethyl methanesulfonate (EMS)-mutagenized maize library and designated it as doi57. In this study, we performed a physiological characterization and transcriptome profiling of doi57 in comparison to corresponding wild-type B73 under drought stress.

Results

Under drought stress, doi57 seedlings displayed lower leaf-surface temperature (LST), faster water loss, and better performance in growth than B73. Transcriptome analysis reveals that key genes involved in flavonoid biosynthesis are enriched among differentially expressed genes in doi57. In line with these results, more flavonols and less hydrogen peroxide (H2O2) were accumulated in guard cells of doi57 than in those of B73 with the decrease of soil water content (SWC). Moreover, the capacity determined from doi57 seedling extracts to scavenge oxygen free radicals was more effective than that of B73 under the drought treatment. Additionally, doi57 seedlings had higher photosynthetic rates, stomatal conductance, transpiration rates, and water use efficiency than B73 exposed to drought stress, resulting in high biomass and greater root/shoot ratios in doi57 mutant plants.

Conclusion

Flavonoids may facilitate maize seedling drought tolerance by lowering drought-induced oxidative damage as well regulating stomatal movement.
The determinants of bootstrap financing in crises: evidence from entrepreneurial ventures in the COVID-19 pandemic
Authors: Block Joern H. , Fisch Christian , Hirschmann Mirko
Published: January 2021

Bootstrap financing refers to measures that entrepreneurial ventures undertake to preserve liquidity (e.g., reducing expenses, collecting receivables, delaying payments, preselling). Prior research shows that bootstrap financing is an important enabler for the growth of resource-constrained early-stage ventures. However, little is known about the use of bootstrap financing in crises, during which the preservation of liquidity is particularly salient. We investigate the determinants of bootstrap financing in the 2020 COVID-19 crisis using a sample of 17,046 German entrepreneurial ventures. We formulate hypotheses about the determinants of bootstrap financing from a necessity, human capital, and opportunity cost perspective. Among others, our results show that the severity of the crisis for the venture, the level of private consumption, and self-employment experience are positively associated with an increased use of bootstrap financing measures. Our study contributes to the literature on bootstrap financing and illuminates how entrepreneurial ventures maintain liquidity in crises.

Plain English SummaryEconomic downturns or crises often lead to financial distress for ventures. To survive such tumultuous times, ventures need to preserve their liquidity. Bootstrap financing refers to measures that entrepreneurial ventures take to preserve liquidity (like sending payment reminders, paying invoices later, reducing tax advances, reducing commercial rent). Because little is known about how bootstrap financing is used during crises, we investigate how it was used during the COVID-19 crisis. Our study builds on a survey of 17,046 German entrepreneurial ventures and self-employed individuals. We find that the use of bootstrap financing is positively related to how severe the crisis was for the venture along with the level of private consumption and self-employment experience of the venture’s owner. In contrast, a negative association exists with private liquidity, business liquidity, how long before the owner retires, and part-time self-employment. The positive association between self-employment experience and bootstrap financing indicates that targeted entrepreneurship education programs or webinars should focus on inexperienced entrepreneurs so that these individuals are prepared to use bootstrapping methods to maintain liquidity during crises.
Determinants of financing constraints
Authors: Santos Anabela , Cincera Michele
Published: January 2021

Using a recursive bivariate probit model and survey data covering the period 2014–2018, the present paper aims to assess which factors in the financial market (supply side) have a higher impact on firms’ likelihood to be financially constrained. The results show that after controlling for potential endogenous bias due to unobservable firm characteristics, being an innovative firm increases the probability of being financially constrained between 21 and 32%. The nature of the innovation strategy also seems to influence the severity of financing constraints. For financially constrained firms, the main factors that limit future financing for growth ambitions are the lack of collateral, bureaucracy, and too high a price. Findings also indicate that measures to facilitate equity investments and making existing public measures easier are the most important factors for future financing while tax incentives only play a minor role.
How Self-Rated is Self-Rated Health? Exploring the Role of Individual and Institutional Factors in Reporting Heterogeneity in Russia
Authors: Baidin Valerii , Gerry Christopher J. , Kaneva Maria
Published: January 2021

In recent years the literature exploring the state dependent nature of individual self-rated health has grown rapidly. We contribute to this ‘reporting heterogeneity’ research field in two main ways. First, we are among the few studies to examine the determinants of reporting heterogeneity in self-rated health in the Russian context. Second, echoing the social determinants of health literature, we augment the standard battery of individual level socioeconomic and demographic characteristics with aggregated macro level variables serving as proxies for local environmental and social conditions. We are not aware of other heterogeneity studies that have incorporated this approach. Estimating a generalized ordered probit model we resolve the identification problem through the inclusion of an objective disease index. In terms of reporting heterogeneity, we find that response behaviour is systematically influenced by individual characteristics but also by aggregate regional socioeconomic characteristics. In particular, the finding that an individual’s relative standing in their local economy can condition their response to subjective health questionnaires is important and merits further examination. We argue that both a relative income mechanism and a mechanism that links the cognitive process of choice with the sense of optimism that individuals have for their institutional environment are plausible explanations for the observed aggregate level effects.
GC-MS/MS analysis of metabolites derived from a single human blastocyst
Authors: Inoue Naomi , Nishida Yoshihiro , Harada Emi , Sakai Kumiko , Narahara Hisashi
Published: January 2021

Introduction

The field of assisted reproductive technology (ART) has significantly advanced; however, morphological evaluation remains as the chosen method of assessment of embryo quality.

Objective

We aimed to examine metabolic changes in embryo culture medium to develop a non-invasive method for evaluation of embryo quality.

Methods

We performed metabolic analysis of culture medium obtained from a single blastocyst cultured for freezing.

Results

In total, 187 (39.8%) of the 469 detectable organic acid metabolites were identified. A significant change (p < 0.05) was observed in eight metabolites between the good-quality and poor-quality embryo groups. Differences were observed in several metabolic pathways between the good-quality and poor-quality embryo groups. Metabolites that showed significant changes were primarily involved in the metabolism of branched-chain amino acids.

Conclusion

The quantification of metabolism in human embryos may assist in identification and selection of good-quality embryos with high rates of survival before freezing and implantation in conjunction with morphological classification. This may help to identify embryos with high rates of survival.
The use of pesticides in Polish agriculture after integrated pest management (IPM) implementation
Authors: Piwowar Arkadiusz
Published: January 2021

The aim of the conducted study was to characterize the attitudes and practices of Polish farmers in the area of performing chemical plant protection treatments. A particular attention was paid to identifying the relationship between the direction of changes in the volume of chemical plant protection product consumption and selected attributes of farms. The main time range of the analyses covered the period of 2013–2017. Statistical data and results of representative surveys carried out on a sample of 1101 farms in Poland were used in the research process. Due to the large number of variants of the analysed variables, a multiple correspondence analysis was used, which made it possible to determine the correlation between the examined features (direction of changes in pesticide use relative to the farm area, economic size of the farm and location of the farm). Statistical analysis showed the existence of strong relationships between the physical (1) and economic (2) size of farms and the direction of changes in pesticide consumption ((1) φ2 = 0.0907; (2) φ2 = 0.1141)). According to empirical studies, the reduction of pesticide consumption took place mainly on the smallest farms. The implementation of the integrated plant protection directive has not resulted in significant changes in the form of reduced pesticide use in large-scale field crops. This raises the need to modify the strategy and model of crop protection in large-scale field crops in Poland.
Do emerging ecosystems and individual capitals matter in entrepreneurial re-entry’ quality and speed?
Authors: Guerrero Maribel , Espinoza-Benavides Jorge
Published: January 2021

This study analyses the influence of environmental and individual conditions on the quality and the speed of entrepreneurial re-entries in emerging economies after a business failure. We propose a conceptual framework supported by the institutional economic theory to study the influence of environmental conditions; and human and social capital to study the influence of individuals’ skills, experiences, and relationships. A retrospective multiple case study analysis was designed to test our conceptual model by capturing longitudinal information on occurred events, trajectory, and determinants of twenty re-entrepreneurs. Our results show that the entrepreneurial experience and type of venture influence the accelerating effect of re-entrepreneurship, as well as how environmental conditions moderate the quality and speed of entrepreneurial re-entries. We provoke a discussion and implications for multiple actors involved in the re-entry of entrepreneurs after a business failure.
Correction to: Trends of Positive Youth Development Publications (1995–2020): A Scientometric Review
Authors: Qi Shaojie , Hua Fengrui , Zhou Zheng , Shek Daniel T. L.
Published: January 2021

A Correction to this paper has been published: 10.1007/s11482-020-09905-3
Diagnostic Criteria for Gastro-esophageal Reflux Following Sleeve Gastrectomy
Authors: Lim Gillian , Johari Yazmin , Ooi Geraldine , Playfair Julie , Laurie Cheryl , Hebbard Geoffrey , Brown Wendy , Burton Paul
Published: January 2021

Background

Gastro-esophageal reflux disease (GERD) post-sleeve gastrectomy (SG) is a controversial issue and diagnostic dilemma. Strong heterogeneity exists in the assessment of reflux post-SG, and better diagnostic tools are needed to characterize symptomatic reflux. We aimed to determine the discriminant factors of symptomatic reflux and establish diagnostic thresholds for GERD following SG.

Materials and Methods

Patients post-SG were categorized into asymptomatic and symptomatic cohorts and completed validated symptom questionnaires. All patients underwent stationary esophageal manometry and 24-h ambulatory pH monitoring. Univariate and multivariate analyses were conducted to determine the strongest discriminant factors for GERD.

Results

Baseline characteristics of the asymptomatic cohort (n = 48) and symptomatic cohort (n = 76) were comparable. The median post-operative duration was 7.3 (14.1) vs 7.5 (10.7) months (p = 0.825). The symptomatic cohort was more female predominant (90.8 vs 72.9%, p = 0.008). Reflux scores were significantly higher in the symptomatic group (36.0 vs 10.5, p = 0.003). Stationary manometry parameters were similar, including hiatus hernia prevalence and impaired esophageal motility. The symptomatic cohort had significantly higher total acid exposure, especially while supine (11.3% vs 0.6%, p < 0.001). Univariate and multivariate regressions delineated reflux score and supine acid exposure as discriminant factors for symptomatic reflux. The thresholds for distinguishing symptomatic reflux are as follows: reflux score of 11.5 (sensitivity 84.0%, specificity 68.2%) and supine acid exposure of 2.65% (sensitivity 67.1%, specificity 70.8%).

Conclusion

A reflux score of 11.5 or more or supine acid exposure of 2.65% or more should be considered diagnostic in defining symptomatic reflux following SG.
Contribution of the requirements engineering to the evaluation of water resources systems efficiency
Authors: Rouissat Bouchrit , Bekkouche Abdelmalek , Smail Nadia
Published: January 2021

In the water resources sector, the need to adopt a new way of thinking based on a systemic approach and analysis is justified by several situations: very complex constraints that accompany the development of the sector, functional interactions between various planned developments and the multitude of actors and stakeholders involved. System engineering is a general methodological approach that encompasses all the appropriate activities to design, evolve and verify a system providing an economical and efficient solution to the needs of customers while satisfying the whole of stakeholders. Based on these concepts of size, the purpose of this paper is to apply the principles of systems engineering for the exploration and evaluation of Boughrara water resources system performance. This system located in the north-west of Algeria involves subsystems in constant interaction, namely mobilization, treatment, purification and transfer of water. Its performance takes into account a number of parameters: compliance with customer satisfaction objectives, system constraints, stakeholder role and responsibility for achieving system-wide objectives, and not relationship with sectors of activity.
Recent increase in European forest harvests as based on area estimates (Ceccherini et al. 2020a) not confirmed in the French case
Authors: Picard Nicolas , Leban Jean-Michel , Guehl Jean-Marc , Dreyer Erwin , Bouriaud Olivier , Bontemps Jean-Daniel , Landmann Guy , Colin Antoine , Peyron Jean-Luc , Marty Pascal
Published: January 2021

• Key message

A recent paper by Ceccherini et al.(2020a) reported an abrupt increase of 30% in the French harvested forest area in 2016–2018 compared to 2004–2015. A re-analysis of their data rather led us to conclude that, when accounting for the singular effect of storm Klaus, the rate of change in harvested area depended on the change year used to separate the two periods to compare. Moreover, the comparison with data on harvested volumes from different sources brought contrasted results depending on the source. Therefore, it cannot be concluded that wood harvest increased in France in 2016–2018 compared to 2004–2015. The discrepancy between Ceccherini et al.’s data and other data on harvested volumes points out the difficulty of reconciling different approaches to estimate wood harvest at a country level.
Much More Than Tribute: The Foreign Policy Instruments of the Ming Empire
Authors: Kuhn Felix
Published: January 2021

The Ming Empire entertained relations with countries all across Asia and beyond. To deal with these many different polities, Ming China relied on a range of foreign policy instruments, among them the granting of special trading rights, the dissemination of cultural objects, and the use of military threats. This article puts the spotlight on the diversity of these foreign policy means. Building on the literature, it takes as its purview all relations that the Ming Empire entertained with foreign polities, exploring the many means that the Ming employed to further their interests. It does so by classifying the instruments into four categories—economic, diplomatic, cultural, and military—showing that the Ming made full use of instruments belonging to each of them.
Glossifungites gingrasi n. isp., a probable subaqueous insect domicile from the Cretaceous Ferron Sandstone, Utah
Authors: King M. Ryan , La Croix Andrew D. , Gates Terry A. , Anderson Paul B. , Zanno Lindsay E.
Published: January 2021

A new ichnospecies, Glossifungites gingrasi n. isp., is described from multiple locations in basal sand-filled coastal plain distributary channels of the Turonian (Upper Cretaceous) Ferron Sandstone (central Utah). Glossifungites gingrasi n. isp. is attributed to the ichnogenus Glossifungites based on the presence of scratch imprints, passive fill, and a tongue-shaped structure, yet the new ichnospecies is distinct because it displays transverse bioglyphs that run perpendicular to the planiform structure, which contrasts to the axis parallel bioglyphs present in the ichnospecies G. saxicava. The transverse arrangement of ornamentation exhibited by G. gingrasi n. isp. is observed in modern subaqueous insect burrows produced by mayfly and chironomid larvae, and constitutes a way to differentiate insect-generated burrows from structures produced by crustaceans that are known to create other Glossifungites ichnospecies. Differentiating insect- from crustacean-generated burrows is significant because it provides a way to distinguish bioturbation by marine-recruited fauna from that produced by freshwater fauna in the rock record, making G. gingrasi n. isp. a valuable ichnological tool for paleoenvironmental and stratigraphic interpretation. While G. gingrasi n. isp. may represent a burrow created by a variety of filter-feeding subaqueous insects, the large size of G. gingrasi n. isp. in the Ferron Sandstone suggests that the largest specimens are probable mayfly burrows and supports the assertion that burrowing mayflies (e.g., Polymitarcyidae and Ephemeridae) adapted to domicile filter-feeding during or prior to the Turonian.

UUID: http://zoobank.org/a033b22f-bf09-481a-975e-3a1b096154cc
THE CASUALTIES OF THELATIN ILIAD
Authors: Horn Fabian
Published: January 2021

The so-calledLatin Iliad, the main source for the knowledge of the Greek epic poem in the Latin West during the Middle Ages, is a hexametric poetic summary (epitome) of Homer'sIliadlikely dating from the Age of Nero, which reduces the 15,693 lines of the original to a mere 1,070 lines (6.8%).
Engaging with the science and politics of biodiversity futures: a literature review
Authors: Wyborn Carina , Louder Elena , Harfoot Mike , Hill Samantha
Published: January 2021

Future global environmental change will have a significant impact on biodiversity through the intersecting forces of climate change, urbanization, human population growth, overexploitation, and pollution. This presents a fundamental challenge to conservation approaches, which seek to conserve past or current assemblages of species or ecosystems in situ. This review canvases diverse approaches to biodiversity futures, including social science scholarship on the Anthropocene and futures thinking alongside models and scenarios from the biophysical science community. It argues that charting biodiversity futures requires processes that must include broad sections of academia and the conservation community to ask what desirable futures look like, and for whom. These efforts confront political and philosophical questions about levels of acceptable loss, and how trade-offs can be made in ways that address the injustices in the distribution of costs and benefits across and within human and non-human life forms. As such, this review proposes that charting biodiversity futures is inherently normative and political. Drawing on diverse scholarship united under a banner of ‘futures thinking’ this review presents an array of methods, approaches and concepts that provide a foundation from which to consider research and decision-making that enables action in the context of contested and uncertain biodiversity futures.
Originalism from the Soft Southern Strategy to the New Right: The Constitutional Politics of Sam Ervin Jr
Authors: SAWYER LOGAN
Published: January 2021

Although originalism’s emergence as an important theory of constitutional interpretation is usually attributed to efforts by the Reagan administration, the role the theory played in the South’s determined resistance to civil rights legislation in the 1960s actually helped create the Reagan coalition in the first place. North Carolina Senator Sam Ervin Jr., the constitutional theorist of the Southern Caucus, developed and deployed originalism because he saw its potential to stymie civil rights legislation and stabilize a Democratic coalition under significant stress. Ervin failed in those efforts, but his turn to originalism had lasting effects. The theory helped Ervin and other conservative southerners explain to outsiders and to themselves why they shifted from support for an interventionist state powerful enough to enforce segregation to an ideology founded on individual rights and liberty. It thus eased the South’s integration with the emerging New Right.
Neurobehavioral correlates of impaired emotion recognition in pediatric PTSD
Authors: Heyn Sara A. , Schmit Collin , Keding Taylor J. , Wolf Richard , Herringa Ryan J.
Published: January 2021

Despite broad evidence suggesting that adversity-exposed youth experience an impaired ability to recognize emotion in others, the underlying biological mechanisms remains elusive. This study uses a multimethod approach to target the neurological substrates of this phenomenon in a well-phenotyped sample of youth meeting diagnostic criteria for posttraumatic stress disorder (PTSD). Twenty-one PTSD-afflicted youth and 23 typically developing (TD) controls completed clinical interview schedules, an emotion recognition task with eye-tracking, and an implicit emotion processing task during functional magnetic resonance imaging )fMRI). PTSD was associated with decreased accuracy in identification of angry, disgust, and neutral faces as compared to TD youth. Of note, these impairments occurred despite the normal deployment of visual attention in youth with PTSD relative to TD youth. Correlation with a related fMRI task revealed a group by accuracy interaction for amygdala–hippocampus functional connectivity (FC) for angry expressions, where TD youth showed a positive relationship between anger accuracy and amygdala–hippocampus FC; this relationship was reversed in youth with PTSD. These findings are a novel characterization of impaired threat recognition within a well-phenotyped population of severe pediatric PTSD. Further, the differential amygdala–hippocampus FC identified in youth with PTSD may imply aberrant efficiency of emotional contextualization circuits.
Increasing secure base script knowledge among parents with Attachment and Biobehavioral Catch-up
Authors: Raby K. Lee , Waters Theodore E. A. , Tabachnick Alexandra R. , Zajac Lindsay , Dozier Mary
Published: January 2021

This study evaluated whether Attachment and Biobehavioral Catch-up (ABC), a parenting intervention, altered the attachment representations of parents (average age of 34.2 years) who had been referred to Child Protective Services (CPS) due to risk for child maltreatment when their children were infants. Approximately 7 years after completing the intervention, parents who had been randomized to receive ABC (n = 43) exhibited greater secure base script knowledge than parents who had been randomized to receive a control intervention (n = 51). Low-risk parents (n = 79) exhibited greater secure base script knowledge than CPS-referred parents who had received a control intervention. However, levels of secure base script knowledge did not differ between low-risk parents and CPS-referred parents who had received the ABC intervention. In addition, secure base script knowledge was positively associated with parental sensitivity during interactions with their 8-year-old children among low-risk and CPS-referred parents. Mediational analyses supported the idea that the ABC intervention enhanced parents’ sensitivity 7 years later indirectly via increases in parents’ secure base script knowledge.
Spikes and localised patterns for a novel Schnakenberg model in the semi-strong interaction regime
Authors: AL SAADI FAHAD , CHAMPNEYS ALAN , GAI CHUNYI , KOLOKOLNIKOV THEODORE
Published: January 2021

An analysis is undertaken of the formation and stability of localised patterns in a 1D Schanckenberg model, with source terms in both the activator and inhibitor fields. The aim is to illustrate the connection between semi-strong asymptotic analysis and the theory of localised pattern formation within a pinning region created by a subcritical Turing bifurcation. A two-parameter bifurcation diagram of homogeneous, periodic and localised patterns is obtained numerically. A natural asymptotic scaling for semi-strong interaction theory is found where an activator source term \[a = O(\varepsilon )\] and the inhibitor source \[b = O({\varepsilon ^2})\], with ε2 being the diffusion ratio. The theory predicts a fold of spike solutions leading to onset of localised patterns upon increase of b from zero. Non-local eigenvalue arguments show that both branches emanating from the fold are unstable, with the higher intensity branch becoming stable through a Hopf bifurcation as b increases beyond the \[O(\varepsilon )\] regime. All analytical results are found to agree with numerics. In particular, the asymptotic expression for the fold is found to be accurate beyond its region of validity, and its extension into the pinning region is found to form the low b boundary of the so-called homoclinic snaking region. Further numerical results point to both sub and supercritical Hopf bifurcation and novel spikeinsertion dynamics.
Mixed Services and Mediated Deservingness: Access to Housing for Migrants in Greece
Authors: Glyniadaki Katerina
Published: January 2021

As the delivery of social services is increasingly carried out by contractors, it is no longer state officials alone who determine clients’ ‘deservingness’. This article draws attention to the interrelated notions of mixed services and mediated deservingness as they apply in the context of migrants’ access to housing in Athens, Greece, during the so-called ‘migration crisis’ of 2015-2017. It argues that non-state actors essentially act as intermediaries between the state and the migrant clients, making their own judgements on the migrants’ deservingness and using their discretionary power accordingly. The findings reveal distinct discretionary patterns among street-level actors who represent migrants, depending on how each interprets the notion of ‘vulnerability’ with regard to gender and age. Although these actors’ room for manoeuvre is framed by the policy framework and the structural conditions in which they operate, their individual normative assumptions play a critical role in shaping their discretionary behaviour towards migrants.
Advantages of a Multi‐Frequency Experiment for Determining the Dielectric Constant of a Layer in a Rectangular Waveguide and Free Space
Authors: Sheina E. A. , Shestopalov Y. V. , Smirnov A. P.
Published: January 2021

An inverse problem of reconstructing real permittivity of a plane‐parallel layer in a perfectly conducting rectangular waveguide or in free space from experimental data using an explicit expression for the scattering matrix is considered. In general, this problem is improperly posed and may be unsolvable due to inaccuracy of the experimental data, and for a perfect noiseless experiment the solution may be not unique because the scattering coefficients curve has self‐intersection points. It is shown that the traditional multi‐frequency method of measurements applied in vector network analyzers can be justified. The following facts are rigorously proved in the paper: nonuniqueness of the solution can be removed if the frequency resolution is sufficiently small; and an algorithm for processing measurement results using least squares provides an approximate solution to the problem that converges to the exact one when the quality of the experiment improves, the convergence rate depends on the number of frequencies used in the experiment.
Laser particles with omnidirectional emission for cell tracking
Authors: Tang Shui-Jing , Dannenberg Paul H. , Liapis Andreas C. , Martino Nicola , Zhuo Yue , Xiao Yun-Feng , Yun Seok-Hyun
Published: January 2021

The ability to track individual cells in space over time is crucial to analyzing heterogeneous cell populations. Recently, microlaser particles have emerged as unique optical probes for massively multiplexed single-cell tagging. However, the microlaser far-field emission is inherently direction-dependent, which causes strong intensity fluctuations when the orientation of the particle varies randomly inside cells. Here, we demonstrate a general solution based on the incorporation of nanoscale light scatterers into microlasers. Two schemes are developed by introducing either boundary defects or a scattering layer into microdisk lasers. The resulting laser output is omnidirectional, with the minimum-to-maximum ratio of the angle-dependent intensity improving from 0.007 (−24 dB) to > 0.23 (−6 dB). After transfer into live cells in vitro, the omnidirectional laser particles within moving cells could be tracked continuously with high signal-to-noise ratios for 2 h, while conventional microlasers exhibited frequent signal loss causing tracking failure.
Correction to: Indole hydrazide compound ZJQ-24 inhibits angiogenesis and induces apoptosis cell death through abrogation of AKT/mTOR pathway in hepatocellular carcinoma
Authors: Liu Jing , Liu Ying , Zhang Jianqiang , Liu Dan , Bao Yafeng , Chen Tianxing , Tang Tao , Lin Jun , Luo Ying , Jin Yi , Zhang Jihong
Published: January 2021

A Correction to this paper has been published: https://doi.org/10.1038/s41419-021-03388-2
Creating Majorana modes from segmented Fermi surface
Authors: Papaj Michał , Fu Liang
Published: January 2021

Majorana bound states provide a fertile ground for both investigation of fundamental phenomena as well as for applications in quantum computation. However, despite enormous experimental and theoretical efforts, the currently available Majorana platforms suffer from a multitude of issues that prevent full realization of their potential. Therefore, improved Majorana systems are still highly sought after. Here we present a platform for creating Majorana bound states from 2D gapless superconducting state in spin-helical systems under the in-plane magnetic or Zeeman field. Topological 1D channels are formed by quantum confinement of quasiparticles via Andreev reflection from the surrounding fully gapped superconducting region. Our proposal can be realized using narrow strips of magnetic insulators on top of proximitized 3D topological insulators. This setup has key advantages that include: small required fields, no necessity of fine-tuning of chemical potential, removal of the low-energy detrimental states, and large attainable topological gap.
Distilling nanoscale heterogeneity of amorphous silicon using tip-enhanced Raman spectroscopy (TERS) via multiresolution manifold learning
Authors: Yang Guang , Li Xin , Cheng Yongqiang , Wang Mingchao , Ma Dong , Sokolov Alexei P. , Kalinin Sergei V. , Veith Gabriel M. , Nanda Jagjit
Published: January 2021

Accurately identifying the local structural heterogeneity of complex, disordered amorphous materials such as amorphous silicon is crucial for accelerating technology development. However, short-range atomic ordering quantification and nanoscale spatial resolution over a large area on a-Si have remained major challenges and practically unexplored. We resolve phonon vibrational modes of a-Si at a lateral resolution of <60 nm by tip-enhanced Raman spectroscopy. To project the high dimensional TERS imaging to a two-dimensional manifold space and categorize amorphous silicon structure, we developed a multiresolution manifold learning algorithm. It allows for quantifying average Si-Si distortion angle and the strain free energy at nanoscale without a human-specified physical threshold. The multiresolution feature of the multiresolution manifold learning allows for distilling local defects of ultra-low abundance (< 0.3%), presenting a new Raman mode at finer resolution grids. This work promises a general paradigm of resolving nanoscale structural heterogeneity and updating domain knowledge for highly disordered materials.
Non-equilibrium metal oxides via reconversion chemistry in lithium-ion batteries
Authors: Hua Xiao , Allan Phoebe K. , Gong Chen , Chater Philip A. , Schmidt Ella M. , Geddes Harry S. , Robertson Alex W. , Bruce Peter G. , Goodwin Andrew L.
Published: January 2021

Binary metal oxides are attractive anode materials for lithium-ion batteries. Despite sustained effort into nanomaterials synthesis and understanding the initial discharge mechanism, the fundamental chemistry underpinning the charge and subsequent cycles—thus the reversible capacity—remains poorly understood. Here, we use in operando X-ray pair distribution function analysis combining with our recently developed analytical approach employing Metropolis Monte Carlo simulations and non-negative matrix factorisation to study the charge reaction thermodynamics of a series of Fe- and Mn-oxides. As opposed to the commonly believed conversion chemistry forming rocksalt FeO and MnO, we reveal the two oxide series topotactically transform into non-native body-centred cubic FeO and zincblende MnO via displacement-like reactions whose kinetics are governed by the mobility differences between displaced species. These renewed mechanistic insights suggest avenues for the future design of metal oxide materials as well as new material synthesis routes using electrochemically-assisted methods.
Structural insights into the disruption of TNF-TNFR1 signalling by small molecules stabilising a distorted TNF
Authors: McMillan David , Martinez-Fleites Carlos , Porter John , Fox David , Davis Rachel , Mori Prashant , Ceska Tom , Carrington Bruce , Lawson Alastair , Bourne Tim , O’Connell James
Published: January 2021

Tumour necrosis factor (TNF) is a trimeric protein which signals through two membrane receptors, TNFR1 and TNFR2. Previously, we identified small molecules that inhibit human TNF by stabilising a distorted trimer and reduce the number of receptors bound to TNF from three to two. Here we present a biochemical and structural characterisation of the small molecule-stabilised TNF-TNFR1 complex, providing insights into how a distorted TNF trimer can alter signalling function. We demonstrate that the inhibitors reduce the binding affinity of TNF to the third TNFR1 molecule. In support of this, we show by X-ray crystallography that the inhibitor-bound, distorted, TNF trimer forms a complex with a dimer of TNFR1 molecules. This observation, along with data from a solution-based network assembly assay, leads us to suggest a model for TNF signalling based on TNF-TNFR1 clusters, which are disrupted by small molecule inhibitors.
Nonequilibrium dynamics of spontaneous symmetry breaking into a hidden state of charge-density wave
Authors: Zhou Faran , Williams Joseph , Sun Shuaishuai , Malliakas Christos D. , Kanatzidis Mercouri G. , Kemper Alexander F. , Ruan Chong-Yu
Published: January 2021

Nonequilibrium phase transitions play a pivotal role in broad physical contexts, from condensed matter to cosmology. Tracking the formation of nonequilibrium phases in condensed matter requires a resolution of the long-range cooperativity on ultra-short timescales. Here, we study the spontaneous transformation of a charge-density wave in CeTe3 from a stripe order into a bi-directional state inaccessible thermodynamically but is induced by intense laser pulses. With ≈100 fs resolution coherent electron diffraction, we capture the entire course of this transformation and show self-organization that defines a nonthermal critical point, unveiling the nonequilibrium energy landscape. We discuss the generation of instabilities by a swift interaction quench that changes the system symmetry preference, and the phase ordering dynamics orchestrated over a nonadiabatic timescale to allow new order parameter fluctuations to gain long-range correlations. Remarkably, the subsequent thermalization locks the remnants of the transient order into longer-lived topological defects for more than 2 ns.
A binding protein regulates myosin-7a dimerization and actin bundle assembly
Authors: Liu Rong , Billington Neil , Yang Yi , Bond Charles , Hong Amy , Siththanandan Verl , Takagi Yasuharu , Sellers James R.
Published: January 2021

Myosin-7a, despite being monomeric in isolation, plays roles in organizing actin-based cell protrusions such as filopodia, microvilli and stereocilia, as well as transporting cargoes within them. Here, we identify a binding protein for Drosophila myosin-7a termed M7BP, and describe how M7BP assembles myosin-7a into a motile complex that enables cargo translocation and actin cytoskeletal remodeling. M7BP binds to the autoinhibitory tail of myosin-7a, extending the molecule and activating its ATPase activity. Single-molecule reconstitution show that M7BP enables robust motility by complexing with myosin-7a as 2:2 translocation dimers in an actin-regulated manner. Meanwhile, M7BP tethers actin, enhancing complex’s processivity and driving actin-filament alignment during processive runs. Finally, we show that myosin-7a-M7BP complex assembles actin bundles and filopodia-like protrusions while migrating along them in living cells. Together, these findings provide insights into the mechanisms by which myosin-7a functions in actin protrusions.
Defect-driven selective metal oxidation at atomic scale
Authors: Zhu Qi , Pan Zhiliang , Zhao Zhiyu , Cao Guang , Luo Langli , Ni Chaolun , Wei Hua , Zhang Ze , Sansoz Frederic , Wang Jiangwei
Published: January 2021

Nanoscale materials modified by crystal defects exhibit significantly different behaviours upon chemical reactions such as oxidation, catalysis, lithiation and epitaxial growth. However, unveiling the exact defect-controlled reaction dynamics (e.g. oxidation) at atomic scale remains a challenge for applications. Here, using in situ high-resolution transmission electron microscopy and first-principles calculations, we reveal the dynamics of a general site-selective oxidation behaviour in nanotwinned silver and palladium driven by individual stacking-faults and twin boundaries. The coherent planar defects crossing the surface exhibit the highest oxygen binding energies, leading to preferential nucleation of oxides at these intersections. Planar-fault mediated diffusion of oxygen atoms is shown to catalyse subsequent layer-by-layer inward oxide growth via atomic steps migrating on the oxide-metal interface. These findings provide an atomistic visualization of the complex reaction dynamics controlled by planar defects in metallic nanostructures, which could enable the modification of physiochemical performances in nanomaterials through defect engineering.
Nanoscale characterization of the biomolecular corona by cryo-electron microscopy, cryo-electron tomography, and image simulation
Authors: Sheibani Sara , Basu Kaustuv , Farnudi Ali , Ashkarran Aliakbar , Ichikawa Muneyoshi , Presley John F. , Bui Khanh Huy , Ejtehadi Mohammad Reza , Vali Hojatollah , Mahmoudi Morteza
Published: January 2021

The biological identity of nanoparticles (NPs) is established by their interactions with a wide range of biomolecules around their surfaces after exposure to biological media. Understanding the true nature of the biomolecular corona (BC) in its native state is, therefore, essential for its safe and efficient application in clinical settings. The fundamental challenge is to visualize the biomolecules within the corona and their relationship/association to the surface of the NPs. Using a synergistic application of cryo-electron microscopy, cryo-electron tomography, and three-dimensional reconstruction, we revealed the unique morphological details of the biomolecules and their distribution/association with the surface of polystyrene NPs at a nanoscale resolution. The analysis of the BC at a single NP level and its variability among NPs in the same sample, and the discovery of the presence of nonspecific biomolecules in plasma residues, enable more precise characterization of NPs, improving predictions of their safety and efficacies.
Dynamic patterns of YAP1 expression and cellular localization in the developing and injured utricle
Authors: Borse Vikrant , Barton Matthew , Arndt Harry , Kaur Tejbeer , Warchol Mark E.
Published: January 2021

The Hippo signaling pathway is a key regulator of tissue development and regeneration. Activation of the Hippo pathway leads to nuclear translocation of the YAP1 transcriptional coactivator, resulting in changes in gene expression and cell cycle entry. Recent studies have demonstrated the nuclear translocation of YAP1 during the development of the sensory organs of the inner ear, but the possible role of YAP1 in sensory regeneration of the inner ear is unclear. The present study characterized the cellular localization of YAP1 in the utricles of mice and chicks, both under normal conditions and after HC injury. During neonatal development, YAP1 expression was observed in the cytoplasm of supporting cells, and was transiently expressed in the cytoplasm of some differentiating hair cells. We also observed temporary nuclear translocation of YAP1 in supporting cells of the mouse utricle after short periods in organotypic culture. However, little or no nuclear translocation of YAP1 was observed in the utricles of neonatal or mature mice after ototoxic injury. In contrast, substantial YAP1 nuclear translocation was observed in the chicken utricle after streptomycin treatment in vitro and in vivo. Together, these data suggest that differences in YAP1 signaling may partially account for the differing regenerative abilities of the avian vs. mammalian inner ear.
Comparative transcriptomics and host-specific parasite gene expression profiles inform on drivers of proliferative kidney disease
Authors: Faber Marc , Shaw Sophie , Yoon Sohye , de Paiva Alves Eduardo , Wang Bei , Qi Zhitao , Okamura Beth , Hartikainen Hanna , Secombes Christopher J. , Holland Jason W.
Published: January 2021

The myxozoan parasite, Tetracapsuloidesbryosalmonae has a two-host life cycle alternating between freshwater bryozoans and salmonid fish. Infected fish can develop Proliferative Kidney Disease, characterised by a gross lymphoid-driven kidney pathology in wild and farmed salmonids. To facilitate an in-depth understanding of T.bryosalmonae-host interactions, we have used a two-host parasite transcriptome sequencing approach in generating two parasite transcriptome assemblies; the first derived from parasite spore sacs isolated from infected bryozoans and the second from infected fish kidney tissues. This approach was adopted to minimize host contamination in the absence of a complete T.bryosalmonae genome. Parasite contigs common to both infected hosts (the intersect transcriptome; 7362 contigs) were typically AT-rich (60–75% AT). 5432 contigs within the intersect were annotated. 1930 unannotated contigs encoded for unknown transcripts. We have focused on transcripts encoding proteins involved in; nutrient acquisition, host–parasite interactions, development, cell-to-cell communication and proteins of unknown function, establishing their potential importance in each host by RT-qPCR. Host-specific expression profiles were evident, particularly in transcripts encoding proteases and proteins involved in lipid metabolism, cell adhesion, and development. We confirm for the first time the presence of homeobox proteins and a frizzled homologue in myxozoan parasites. The novel insights into myxozoan biology that this study reveals will help to focus research in developing future disease control strategies.
Association of serum lipopolysaccharide-binding protein level with sensitization to food allergens in children
Authors: Ha Eun Kyo , Kim Ju Hee , Yon Dong Keon , Lee Seung Won , Kim Mi Ae , Lee Kyung Suk , Sung Myongsoon , Jee Hye Mi , Shin Youn Ho , Han Man Yong
Published: January 2021

Lipopolysaccharide (LPS)-binding protein (LBP) is an acute-phase reactant that mediates innate immune responses triggered by LPS. Recent studies indicated a positive correlation of circulating LBP level with chronic low-grade inflammation, a condition present in many non-communicable diseases. We determined the association of serum LBP concentration with allergic sensitization in a general pediatric population. Serum LBP was measured in a sample of children (n = 356; mean age = 9.6 ± 0.2 years) in this population-based cross-sectional study. Skin prick tests (SPTs) were performed to assess allergic sensitization to 22 common inhalant and food allergens. One hundred and seven children (30.1%) were nonsensitized, 160 (44.9%) were monosensitized, and 89 (25.0%) were polysensitized. Children who were mono- or polysensitized had a significantly higher median serum LBP level (25.5 ng/mL, inter-quartile range [IQR] 20.3–30.7) than those who were nonsensitized (20.3 ng/mL, IQR = 14.81–25.8,P < 0.0001). Multivariate logistic regression analysis with adjustment for confounders indicated that serum LBP level was positively associated with allergic sensitization overall (adjusted odds ratio [aOR] 1.041; 95% CI 1.007–1.076,P = 0.016), with sensitization to food allergens in particular (aOR 1.080, 95% CI 1.029–1.133,P = 0.002), but not with sensitization to aeroallergens (aOR 1.010, 95% CI 0.982–1.040,P = 0.467). LBP level was not associated with allergic diseases after adjustment. We suggest the possibility of sensitization to food allergens may be related to gut-derived low-grade inflammation, and large sized longitudinal investigations are needed to elucidate the relationship.