bluuebunny/crossref_metadata_2025 huggingface dataset:
Constructivism‐informed variation theory lesson designs in enriching and elevating science learning: Case studies of seamless learning design
Authors: Voon Xin P. , Wong Lung H. , Looi Chee K. , Chen Wenli
Published: February 2020

The constructivist paradigm opens abundant opportunities for effective knowledge construction in which student build knowledge and continually evaluated and improved their knowledge. The teaching mode under constructivist pedagogy redefines the role of students and the teachers and their interrelationships by creating a nurturing environment. By adapting constructivist framework, this article demonstrates how the variation of learning practices was critical in facilitating Primary 4 students in Singapore to carry out seamless science learning. The variation of learning practices enables the students to explore a particular scientific concept through various learning experience across the contexts. The study adapted the framework of the Objects of Constructivist Learning Model for the improvement of the seamless science learning design. When redesigning the lesson, a conscious effort was made by the teacher to create relevant patterns of variation, that is, varying certain critical aspect(s) while keeping other aspects of the object of learning invariant in order to help students discern those critical aspects. The findings contribute knowledge to how the Theory of Variation can be used in analyzing seamless learning as well as designing for constructivist learning experiences. The findings have also demonstrated that the complementary practice of constructivist pedagogy with variation theory as a viable and effective approach in seamless science learning, at which it deepened students' understanding through constructing the critical aspects of a phenomenon. Engagement with primary school students in experiencing the variations allowed the translation of theory into practice.
Investigation of chemical constituents and cytotoxic activity of the lichen Usnea undulata
Authors: Tram Nguyen Thi Thu , Anh Dinh Hoang , Thuc Huynh Hoang , Tuan Nguyen Trong
Published: February 2020

Lichens are a promising source of good anticancer agents. However the study on their bioactivities remains limited, especially in Vietnam. In this study, three extracts of lichen Usnea undulata Stirt. including n‐hexane, acetone and methanol were investigated for their cytotoxic activity on two human cancer cell lines (MCF‐7, NCI‐H460) and normal fibroblasts by sulforhodamine B (SRB) assay. The results showed that the n‐hexane extract exhibited the highest inhibition activity with IC50 5.26±0.13 μg/mL for MCF‐7 and 6.83±0.64 μg/mL for NCI‐H460, followed by acetone extract with IC50 66.44±1.37 μg/mL and 92.14±1.49 μg/mL, respectively. The methanol extract possessed weak cytotoxic effect against MCF‐7 and NCI‐H460 (IC50 values more than 100 μg/mL). The n‐hexane extract demonstrated interesting activity particularly on MCF‐7 as good selectivity index was recorded (SI > 3). The phytochemical study on n‐hexane and acetone extracts led to the isolation of four compounds including usnic acid (1), methyl orsellinate (2), methyl β‐orsellinate (3), 7‐hydroxyl‐5‐methoxy‐6‐methylphtalide (4) in which compound (4) was isolated the first time in such species. Their structures were elucidated by NMR analysis and compared with literature data.
Corrosion protection of carbon steel by polyurethane coatings containing graphene oxide
Authors: Duong Nguyen Thuy , An Tran Boi , Thao Phan Thanh , Oanh Vu Ke , Truc Trinh Anh , Vu Pham Gia , Hang To Thi Xuan
Published: February 2020

In this work, graphene oxide (GO) was prepared by modified Hummer's method. Polyurethane coatings with different GO concentrations (0.1‐0.5 %) were prepared for corrosion protection of carbon steel. Synthesized GO was characterized by FTIR and XRD. Corrosion resistance of polyurethane coatings containing GO was investigated by electrochemical impedance spectroscopy and salt fog test. The effects of GO on protection performance of polyurethane coatings depended on its dispersion ability. GO at a concentration of 0.1 % significantly improved corrosion resistance of polyurethane coatings.
Flavonoids from Camellia sinensis
Authors: Cuc Nguyen Thi , Nhiem Nguyen Xuan , Tai Bui Huu , Yen Pham Hai , Van Kiem Phan
Published: February 2020

Six flavonoids camelliquercetiside C (1), epigallocatechin 3‐O‐gallate (2), rutin (3), quercetin‐3‐O‐β‐D‐glucopyranoside (4), epicatechin (5), and epigallocatechin (6) were isolated from the methanol extract of the leaves of Camellia sinensis by using combined chromatographic methods. Their structures were identified on the basis of spectroscopic evidence and by comparison with those reported in the literature.
Optimization of conditions for extraction of total polyphenols from dried tumeric (Curcuma longa L.) leaves using Response Surface Methodology
Authors: Thach Nguyen Ai
Published: February 2020

Turmeric (Curcuma longa Linn) is a member of the Zingiberaceae family which is cultivated in tropical such as Vietnam and subtropical regions on over the world. Response surface method was used to optimize polyphenol compounds from dried tumeric leaves in different extraction conditions. Three main factors effect on total polyphenol content from dried tumeric leaves that include: extraction temperature (50, 60, and 70 oC), duration (40, 50, and 60 minutes), and solvent concentration (40, 50, and 60 %). The results of research showed that the optimal extraction condition of polyphenol from tumeric leaves was temperature at 68.3 oC for 59.9 minutes and 40 % ethanol that would give the highest polyphenols content 64.2 mg GAE/g DW. The results of this research indicated that the potential of using tumeric leaves as sources of natural antioxidant compounds.
The Pivotal Role of N‐O bonds in the Synthesis of Natural Products: A mini‐review
Authors: Kouklovsky Cyrille
Published: February 2020

This review focuses on the role of the nitrogen‐oxygen bond as a structural cornerstone for the construction of complex natural products. This bond may play several roles such as a functional protecting group or an activating group in carbonyl chemistry. Compounds containing a N‐O bond are generally prepared by cycloaddition of nitroso derivatives, nitrones or nitriles oxides. The first two reactions have been used in the synthesis of a N‐O bond containing natural product, pyrinodemin A, or for the synthesis of hydroxylated piperidine alkaloids after N‐O bond cleavage.
Higgs Quark Flavor Violation: Simplified Models and Status of General Two-Higgs-Doublet Model
Authors: Herrero-Garcia Juan , Nebot Miguel , Rajec Filip , White Martin , Williams Anthony G.
Published: February 2020

Abstract

We study quark flavor violating interactions mediated by the Higgs boson h. We consider observables involving a third generation quark, of both the up and the down quark sectors, like h → bs and t → ch. Using an effective field theory approach we systematically list all the possible tree-level ultraviolet completions, which comprise models with vector-like quarks and/or extra scalars. We provide upper bounds on the flavor violating transitions allowed by current limits stemming from low energy processes, such as meson mixing and b → sγ. We find that scenarios with vector-like quarks always have very suppressed flavor-violating transitions, while a general Two-Higgs-Doublet Model may have a sizeable rate. To study the latter case in detail, we perform a full numerical simulation taking into account all relevant theoretical and phenomenological constraints. Our results show that BR(t → ch) [BR(h → bs)] are still allowed at the sub-percent [percent] level, which are being [may be] explored at the LHC [future colliders]. Finally, we have found that the mild mass-splitting discrepancy with respect to the SM in the Bs meson system can be accommodated in the Two-Higgs-Doublet Model. If confirmed, it yields the prediction BR(h → bs) ≃ 10−4, if the new contribution to the mass-splitting is dominated by tree-level Higgs boson exchange.
Magnetically charged AdS5 black holes from class $$ \mathcal{S} $$ theories on hyperbolic 3-manifolds
Authors: Bae Jin-Beom , Gang Dongmin , Lee Kimyeong
Published: February 2020

Abstract

We study the twisted index of 4d $$ \mathcal{N} $$
N
= 2 class $$ \mathcal{S} $$
S
theories on a closed hyperbolic 3-manifold M3. Via 6d picture, the index can be written in terms of topological invariants called analytic torsions twisted by irreducible flat connections on the 3-manifold. Using the topological expression, we determine the full perturbative 1/N expansion of the twisted index. The leading part nicely matches the Bekestein-Hawking entropy of a magnetically charged black hole in the holographic dual AdS5 with AdS2 × M3 near-horizon.
Historical sunspot records
Authors: Arlt Rainer , Vaquero José M.
Published: February 2020

Sunspot observations are available in fairly good numbers since 1610, after the invention of the telescope. This review is concerned with those sunspot observations of which longer records and drawings in particular are available. Those records bear information beyond the classical sunspot numbers or group sunspot numbers. We begin with a brief summary on naked-eye sunspot observations, in particular those with drawings. They are followed by the records of drawings from 1610 to about 1900. The review is not a compilation of all known historical sunspot information. Some records contributing substantially to the sunspot number time series may therefore be absent. We also glance at the evolution of the understanding of what sunspots actually are, from 1610 to the 19th century. The final part of the review illuminates the physical quantities that can be derived from historical drawings.
Collecting egocentric network data with visual tools: A comparative study
Authors: Hollstein Betina , Töpfer Tom , Pfeffer Jürgen
Published: February 2020

When collecting egocentric network data, visual representations of networks can function as a cognitive aid for depicting relationships, helping to maintain an overview of the relationships, and keeping the attention of the interviewees. Additionally, network maps can serve as a narration generator in qualitative and in mixed-methods studies. While varying visual instruments are used for collecting egocentric network data, little is known about differences among visual tools concerning the influence on the resulting network data, the usability for interviewees, and data validity. The article provides an overview of existing visually oriented tools that are used to collect egocentric networks and discusses their functions, advantages, and limitations. Then, we present results of an experimental study where we compare four different visual tools with regard to networks elicited, manageability, and the impact of follow-up questions. In order to assess the manageability of the four tools, we used the thinking aloud method. The results provide evidence that the decision in favor of a specific visual tool (structured vs. unstructured) can affect the size and composition of the elicited networks. Follow-up questions greatly affect the elicited networks and follow-up cues can level out differences among tools. Respondents tend to prefer the concentric circles tool, with some differences in preferences and manageability of tools between participants with low and those with high socioeconomic status. Finally, assets and drawbacks of the four instruments are discussed with regard to data quality and crucial aspects of the data collection process when using visual tools.
A mediation model for relational aggression, victimization, attachment, and depressive symptoms in Guam: A gender-informed approach
Authors: Kawabata Yoshito , Nakamura Monique S , De Luna Mc Jason F
Published: February 2020

The present study examined the association between relational aggression and depressive symptoms, and the serial mediation of relational victimization and attachment insecurity in this association from a gender-informed approach. Participants consisted of 35 students (77% female; age: 18–25) for the pilot qualitative study and 206 students (68% female; age: 18–25) for the main quantitative study. Both sets of participants were recruited at the same public university in Guam. The qualitative data were transcribed verbatim and coded by three trained researchers (interrater agreement = 90%). From the qualitative data, several themes, such as relational aggression and victimization, physical aggression and victimization, negative affect and emotion, and culture emerged. All participants reported the use of relational aggression and showing negative emotions in a close relationship. Gender differences in the content of the themes were also found, such that relational aggression and victimization seemed to be more emotionally stressful for women than men. In line with these qualitative findings, the quantitative data showed that relational aggression was associated with depressive symptoms, and this association was mediated by relational victimization and attachment anxiety (not avoidance) only for women, while the contributions of physical aggression and victimization were controlled for. No direct and indirect links for physical aggression was evidenced. These findings are discussed from clinical, developmental and cultural perspectives.
Slab break-off origin of 105 Ma A-type porphyritic granites in the Asa area of Tibet
Authors: Li Hang , Wang Ming , Zeng Xiao-Wen , Luo An-Bo , Yu Yun-Peng , Zeng Xian-Jin
Published: February 2020

The study of the petrogenesis of some magmatic rocks with special geochemical attributes provides effective information for us to explore the deep geodynamic background of their formation. A series of granitic porphyry dykes have been found in the mélange zone of the Asa region in southern Tibet, whose genesis may be closely related to the evolution of the Meso-Tethyan Ocean. Regional geodynamic evolution is investigated by whole-rock geochemical analysis, zircon U–Pb dating and Lu–Hf isotopic analysis of two porphyritic granites. The Asa porphyritic granites have high SiO2(74.29–78.65 wt %) and alkalis (Na2O + K2O = 6.51–9.35 wt %) contents, and low Al2O3(11.60–14.51 wt %), CaO (0.04–0.19 wt MgO (0.01–0.10 wt %) contents. They are enriched in Zr, Nb, Ce, Y and Hf and depleted in Ti, Ba, Sr and P, consistent with A-type granites. The samples are relatively rich in LREEs, with LREE/HREE ratios of 1.73–3.04. They display negative Eu anomalies (Eu/Eu* = 0.24–0.28) and obvious Ce anomalies in some samples. Zircon U–Pb analyses show that the porphyritic granites formed in late Early Cretaceous time, 107.4 to 105.5 Ma. Zircon εHf(t) values are in the range of 6.9 to 12.0. These data indicate that the porphyritic granites were sourced from interaction between mantle-derived and juvenile lower crust-derived melts, with the addition of oceanic sediment-derived melts. This occurred when the subducting Bangong–Nujiang oceanic crust split to create a slab window. Rising asthenosphere triggered re-melting of lower crust basalts, resulting in the formation of the late Early Cretaceous A-type granites around Asa.
Immigration, Plenary Powers, and Sovereignty Talk: Then and Now
Authors: Lim Julian
Published: February 2020

This essay surveys the changes and continuities in U.S. immigration law and policy between the Gilded Age and the 1990s–2010s. It points to how the administration of immigration law today is rooted in doctrines established in late nineteenth-century immigration cases. In particular, the essay connects current anxieties over immigration, borders, and national sovereignty to the “plenary power” doctrine that came out of the Supreme Court's decision inChae Chan Ping v. United States(1889). Examining recent federal actions to “secure” the border and enforce immigration law, this essay begins to address the ways in which current policy continues to reflect Gilded Age anxieties about territory, sovereignty, migration, and diverse populations during an era of constantly shifting borders.
Experimental validation of a dual-receiver radar architecture for snowpack monitoring
Authors: Pasian Marco , Espín-López Pedro Fidel , Silvestri Lorenzo , Barbolini Massimiliano , Dell'Acqua Fabio
Published: February 2020

Microwave radars can be used to monitor the internal structure of the snowpack, delivering real-time and non-destructive measurements. Recently, the working principle of an innovative radar architecture able to identify some of the most important snowpack parameters, without external aids, has been demonstrated. A key point of this new architecture is the use of two independent receiving antennas, and one transmitting antenna. This paper presents a comparison between two different implementations, either based on one physical antenna miming two receiving antennas, or based directly on two physical receiving antennas. The different advantages and disadvantages of both solutions are discussed, highlighting the superior accuracy achieved by the implementation based on two physical receiving antennas. Then, this paper also presents the field results achieved by this type of radar architecture, on the grounds of a 5-day experimental campaign that took place in winter 2019 in the Italian Alps on dry snow. The comparison between the radar measurements and the ground truth (manual snowpit analysis, in terms of snowpack depth, dielectric constant, bulk density, and snow water equivalent) is provided. Overall, a root mean square error of around 3.5 cm, 0.05, 27 kg/m3, and 2.5 cm is achieved, respectively.
Time of wild oat (Avena fatua) panicle clipping influences seed viability
Authors: Tidemann Breanne D. , Harker K. Neil , Johnson Eric N. , Willenborg Christian J. , Shirtliffe Steve J.
Published: February 2020

Wild oat (Avena fatua L.) is one of the most problematic weed species in western Canada due to widespread populations, herbicide resistance, and seed dormancy. In wheat (Triticum aestivum L.), and especially in shorter crops such as lentil (Lens culinaris Medik.), A. fatua seed panicles elongate above the crop canopy, which can facilitate physical cutting of the panicles (clipping) to reduce viable seed return to the seedbank. However, the viability of A. fatua seed at the time of panicle elongation is not known. The objective of this study was to determine the viability of A. fatua seed at successive time intervals after elongation above a wheat or lentil crop canopy. A 2-yr panicle clipping and removal study in wheat and lentil was conducted in Lacombe, AB, and Saskatoon, SK, in 2015 and 2016 to determine the onset of viability in A. fatua seeds at successive clipping intervals. Manual panicle clipping of A. fatua panicles above each crop canopy began when the majority of panicles were visible above respective crop canopies and continued weekly until seed shed began. At the initiation of panicle clipping, A. fatua seed viability was between 0% and 10%. By the last clipping treatment (approximately 6 to 7 wk after elongation), 95% of the A. fatua seeds were viable. Seed moisture and awn angle were not good predictors of A. fatua viability, and therefore were unlikely to provide effective tools to estimate appropriate timing for implementation of A. fatua clipping as a management technique. Based on A. fatua seed viability, earlier clipping of A. fatua is likely to be more effective in terms of population management and easier to implement in shorter crops such as lentil. Investigations into long-term effects of clipping on A. fatua populations are needed to evaluate the efficacy of this management strategy on A. fatua.
Interindividual Differences in Cognitive Functioning Are Associated	with Autobiographical Memory Retrieval Specificity in Older	Adults
Authors: Peters Sarah , Sheldon Signy
Published: February 2020

Abstract. We examined whether interindividual differences in cognitive functioning among older adults are related to episodic memory engagement during autobiographical memory retrieval. Older adults ( n = 49, 24 males; mean age = 69.93; mean education = 15.45) with different levels of cognitive functioning, estimated using the Montreal Cognitive Assessment (MoCA), retrieved multiple memories (generation task) and the details of a single memory (elaboration task) to cues representing thematic or event-specific autobiographical knowledge. We found that the MoCA score positively predicted the proportion of specific memories for generation and episodic details for elaboration, but only to cues that represented event-specific information. The results demonstrate that individuals with healthy, but not unhealthy, cognitive status can leverage contextual support from retrieval cues to improve autobiographical specificity.
The Stationary Banding Complex and Secondary Eyewall Formation in Tropical Cyclones
Authors: Vaughan Anna , Walsh Kevin J. E. , Kepert Jeffrey D.
Published: February 2020

89 GHz passive microwave satellite data are used to develop a five year climatology of the incidence and morphology of the stationary banding complex in tropical cyclones and quantify changes in convective morphology prior to secondary eyewall formation. The stationary banding complex is shown to be present in 39% of passive microwave overpasses. Morphology varies substantially between tropical cyclones, with crossing angles ranging from 0.19° to 61.78° and azimuthal extents from 0.29
to 4.02
radians. Variations in the incidence and geometry of the stationary banding complex are observed in different environmental conditions and geographic locations. For 84 secondary eyewall formation events included in the sample, a stationary banding complex is observed within 6 hr of the secondary eyewall developing in 79% of cases. Within 12 hr prior to secondary eyewall formation, the crossing angle is significantly lower than its sample median, while the azimuthal extent is higher than its sample median. These results demonstrate that secondary eyewall formation is (most) often preceded by the formation and axisymmetrization of a stationary banding complex.
Thank You to Our 2019 Reviewers
Authors: Faccenna Claudio , Becker Thorsten , Behr Whitney , Blichert‐Toft Janne , Edmonds Marie , Faul Ulrich , Feinberg Joshua , Long Maureen , Lithgow‐Bertelloni Carolina R. , Paytan Adina , van der Beek Peter , Williams Branwen
Published: February 2020

The publishing process relies on the work of volunteer reviewers, and evaluating the interdisciplinary papers published in G‐Cubed can be challenging. As Editors and Associate Editors, we would like to give our appreciation to all reviewers and would like to acknowledge them in this editorial. G‐Cubed published 326 manuscripts out of 650 submissions in 2019, thanks on the efforts of 860 dedicated reviewers. Their names are listed below, and in italics are those who provided three or more reviews. A big thank you from the G‐Cubed team!
Identifying conserved molecular targets required for cell migration of glioblastoma cancer stem cells
Authors: Volovetz Josephine , Berezovsky Artem D. , Alban Tyler , Chen Yujun , Lauko Adam , Aranjuez George F. , Burtscher Ashley , Shibuya Kelly , Silver Daniel J. , Peterson John , Manor Danny , McDonald Jocelyn A. , Lathia Justin D.
Published: February 2020

Glioblastoma (GBM) is the most prevalent primary malignant brain tumor and is associated with extensive tumor cell infiltration into the adjacent brain parenchyma. However, there are limited targeted therapies that address this disease hallmark. While the invasive capacity of self-renewing cancer stem cells (CSCs) and their non-CSC progeny has been investigated, the mode(s) of migration used by CSCs during invasion is currently unknown. Here we used time-lapse microscopy to evaluate the migratory behavior of CSCs, with a focus on identifying key regulators of migration. A head-to-head migration assay demonstrated that CSCs are more invasive than non-CSCs. Time-lapse live cell imaging further revealed that GBM patient-derived CSC models either migrate in a collective manner or in a single cell fashion. To uncover conserved molecular regulators responsible for collective cell invasion, we utilized the genetically tractable Drosophila border cell collective migration model. Candidates for functional studies were generated using results from a targeted Drosophila genetic screen followed by gene expression analysis of the human homologs in GBM tumors and associated GBM patient prognosis. This strategy identified the highly conserved small GTPase, Rap1a, as a potential regulator of cell invasion. Alteration of Rap1a activity impaired the forward progress of Drosophila border cells during development. Rap1a expression was elevated in GBM and associated with higher tumor grade. Functionally, the levels of activated Rap1a impacted CSC migration speed out of spheres onto extracellular matrix. The data presented here demonstrate that CSCs are more invasive than non-CSCs, are capable of both collective and single cell migration, and express conserved genes that are required for migration and invasion. Using this integrated approach, we identified a new role for Rap1a in the migration of GBM CSCs.
SET7/9 promotes multiple malignant processes in breast cancer development via RUNX2 activation and is negatively regulated by TRIM21
Authors: Si Wenzhe , Zhou Jiansuo , Zhao Yang , Zheng Jiajia , Cui Liyan
Published: February 2020

Although the deregulation of lysine methyltransferase (su(var)-3–9, enhancer-of-zeste, trithorax) domain-containing protein 7/9 (SET7/9) has been identified in a variety of cancers, the potential role of SET7/9 and the molecular events in which it is involved in breast cancer remain obscure. Using the online Human Protein Atlas and GEO databases, the expression of SET7/9 was analyzed. Furthermore, we investigated the underlying mechanisms using chromatin immunoprecipitation-based deep sequencing (ChIP-seq) and quantitative ChIP assays. To explore the physiological role of SET7/9, functional analyses such as CCK-8, colony formation, and transwell assays were performed and a xenograft tumor model was generated with the human breast cancer cell lines MCF-7 and MDA-MB-231. Mass spectrometry, co-immunoprecipitation, GST pull-down, and ubiquitination assays were used to explore the mechanisms of SET7/9 function in breast cancer. We evaluated the expression of SET7/9 in different breast cancer cohorts and found that higher expression indicated worse survival times in these public databases. We demonstrated positive effects of SET7/9 on cell proliferation, migration, and invasion via the activation of Runt-related transcription factor 2 (RUNX2). We demonstrate that tripartite motif-containing protein 21 (TRIM21) physically associates with SET7/9 and functions as a major negative regulator upstream of SET7/9 through a proteasome-dependent mechanism and increased ubiquitination. Taken together, our data suggest that SET7/9 has a promoting role via the regulation of RUNX2, whereas TRIM21-mediated SET7/9 degradation acts as an anti-braking system in the progression of breast cancer.
Dictionary learning in Fourier-transform scanning tunneling spectroscopy
Authors: Cheung Sky C. , Shin John Y. , Lau Yenson , Chen Zhengyu , Sun Ju , Zhang Yuqian , Müller Marvin A. , Eremin Ilya M. , Wright John N. , Pasupathy Abhay N.
Published: February 2020

Modern high-resolution microscopes are commonly used to study specimens that have dense and aperiodic spatial structure. Extracting meaningful information from images obtained from such microscopes remains a formidable challenge. Fourier analysis is commonly used to analyze the structure of such images. However, the Fourier transform fundamentally suffers from severe phase noise when applied to aperiodic images. Here, we report the development of an algorithm based on nonconvex optimization that directly uncovers the fundamental motifs present in a real-space image. Apart from being quantitatively superior to traditional Fourier analysis, we show that this algorithm also uncovers phase sensitive information about the underlying motif structure. We demonstrate its usefulness by studying scanning tunneling microscopy images of a Co-doped iron arsenide superconductor and prove that the application of the algorithm allows for the complete recovery of quasiparticle interference in this material.
Response outcomes gate the impact of expectations on perceptual decisions
Authors: Hermoso-Mendizabal Ainhoa , Hyafil Alexandre , Rueda-Orozco Pavel E. , Jaramillo Santiago , Robbe David , de la Rocha Jaime
Published: February 2020

Perceptual decisions are based on sensory information but can also be influenced by expectations built from recent experiences. Can the impact of expectations be flexibly modulated based on the outcome of previous decisions? Here, rats perform an auditory task where the probability to repeat the previous stimulus category is varied in trial-blocks. All rats capitalize on these sequence correlations by exploiting a transition bias: a tendency to repeat or alternate their previous response using an internal estimate of the sequence repeating probability. Surprisingly, this bias is null after error trials. The internal estimate however is not reset and it becomes effective again after the next correct response. This behavior is captured by a generative model, whereby a reward-driven modulatory signal gates the impact of the latent model of the environment on the current decision. These results demonstrate that, based on previous outcomes, rats flexibly modulate how expectations influence their decisions.
Fatigue-resistant adhesion of hydrogels
Authors: Liu Ji , Lin Shaoting , Liu Xinyue , Qin Zhao , Yang Yueying , Zang Jianfeng , Zhao Xuanhe
Published: February 2020

The adhesion of soft connective tissues (tendons, ligaments, and cartilages) on bones in many animals can maintain high toughness (∽800 J m−2) over millions of cycles of mechanical loads. Such fatigue-resistant adhesion has not been achieved between synthetic hydrogels and engineering materials, but is highly desirable for diverse applications such as artificial cartilages and tendons, robust antifouling coatings, and hydrogel robots. Inspired by the nanostructured interfaces between tendons/ligaments/cartilages and bones, we report that bonding ordered nanocrystalline domains of synthetic hydrogels on engineering materials can give a fatigue-resistant adhesion with an interfacial fatigue threshold of 800 J m−2, because the fatigue-crack propagation at the interface requires a higher energy to fracture the ordered nanostructures than amorphous polymer chains. Our method enables fatigue-resistant hydrogel coatings on diverse engineering materials with complex geometries. We further demonstrate that the fatigue-resistant hydrogel coatings exhibit low friction and low wear against natural cartilages.
Predominant regional biophysical cooling from recent land cover changes in Europe
Authors: Huang Bo , Hu Xiangping , Fuglstad Geir-Arne , Zhou Xu , Zhao Wenwu , Cherubini Francesco
Published: February 2020

Around 70 Mha of land cover changes (LCCs) occurred in Europe from 1992 to 2015. Despite LCCs being an important driver of regional climate variations, their temperature effects at a continental scale have not yet been assessed. Here, we integrate maps of historical LCCs with a regional climate model to investigate air temperature and humidity effects. We find an average temperature change of −0.12 ± 0.20 °C, with widespread cooling (up to −1.0 °C) in western and central Europe in summer and spring. At continental scale, the mean cooling is mainly correlated with agriculture abandonment (cropland-to-forest transitions), but a new approach based on ridge-regression decomposing the temperature change to the individual land transitions shows opposite responses to cropland losses and gains between western and eastern Europe. Effects of historical LCCs on European climate are non-negligible and region-specific, and ignoring land-climate biophysical interactions may lead to sub-optimal climate change mitigation and adaptation strategies.
Structure of the G protein chaperone and guanine nucleotide exchange factor Ric-8A bound to Gαi1
Authors: McClelland Levi J. , Zhang Kaiming , Mou Tung-Chung , Johnston Jake , Yates-Hansen Cindee , Li Shanshan , Thomas Celestine J. , Doukov Tzanko I. , Triest Sarah , Wohlkonig Alexandre , Tall Gregory G. , Steyaert Jan , Chiu Wah , Sprang Stephen R.
Published: February 2020

Ric-8A is a cytosolic Guanine Nucleotide exchange Factor (GEF) that activates heterotrimeric G protein alpha subunits (Gα) and serves as an essential Gα chaperone. Mechanisms by which Ric-8A catalyzes these activities, which are stimulated by Casein Kinase II phosphorylation, are unknown. We report the structure of the nanobody-stabilized complex of nucleotide-free Gα bound to phosphorylated Ric-8A at near atomic resolution by cryo-electron microscopy and X-ray crystallography. The mechanism of Ric-8A GEF activity differs considerably from that employed by G protein-coupled receptors at the plasma membrane. Ric-8A engages a specific conformation of Gα at multiple interfaces to form a complex that is stabilized by phosphorylation within a Ric-8A segment that connects two Gα binding sites. The C-terminus of Gα is ejected from its beta sheet core, thereby dismantling the GDP binding site. Ric-8A binds to the exposed Gα beta sheet and switch II to stabilize the nucleotide-free state of Gα.
Concept of a Radiofrequency Device for Osteopenia/Osteoporosis Screening
Authors: Makarov Sergey N. , Noetscher Gregory M. , Arum Seth , Rabiner Robert , Nazarian Ara
Published: February 2020

Osteoporosis represents a major health problem, resulting in substantial increases in health care costs. There is an unmet need for a cost-effective technique that can measure bone properties without the use of ionizing radiation. The present study reports design, construction, and testing of a safe, and easy to use radiofrequency device to detect osteoporotic bone conditions. The device uses novel on-body antennas contacting the human wrist under an applied, operator-controlled pressure. For the dichotomous diagnostic test, we selected 60 study participants (23–94 years old, 48 female, 12 male) who could be positively differentiated between healthy and osteopenic/osteoporotic states. The band-limited integral of the transmission coefficient averaged for both wrists, multiplied by age, and divided by BMI has been used as an index. For a 100 MHz frequency band centered about 890–920 MHz, the maximum Youden’s J index is 81.5%. Both the sensitivity and specificity simultaneously reach 87% given the calibration device threshold tolerance of ±3%. Our approach correlates well with the available DXA measurements and has the potential for screening patients at risk for fragility fractures, given the ease of implementation and low costs associated with both the technique and the equipment. The inclusion of radiofrequency transmission data does add supplementary useful information to the available clinical risk factors.
Optimization of culture conditions for differentiation of melon based on artificial neural network and genetic algorithm
Authors: Zhang Qiang , Deng Dandan , Dai Wenting , Li Jixin , Jin Xinwen
Published: February 2020

Artificial neural network is an efficient and accurate fitting method. It has the function of self-learning, which is particularly important for prediction, and it could take advantage of the computer’s high-speed computing capabilities and find the optimal solution quickly. In this paper, four culture conditions: agar concentration, light time, culture temperature, and humidity were selected. And a three-layer neural network was used to predict the differentiation rate of melon under these four conditions. Ten-fold cross validation revealed that the optimal back propagation neural network was established with traingdx as the training function and the final architecture of 4-3-1 (four neurons in the input layer, three neurons in the hidden layer and one neuron in the output layer), which yielded a high coefficient of correlation (R2, 0.9637) between the actual and predicted outputs, and a root-mean-square error (RMSE) of 0.0108, suggesting that the artificial neural network worked well. According to the optimal culture conditions generated by genetic algorithm, tissue culture experiments had been carried out. The results showed that the actual differentiation rate of melon reached 90.53%, and only 1.59% lower than the predicted value of genetic algorithm. It was better than the optimization by response surface methodology, which the predicted induced differentiation rate is 86.04%, the actual value is 83.62%, and was 2.89% lower than the predicted value. It can be inferred that the combination of artificial neural network and genetic algorithm can optimize the plant tissue culture conditions well and with high prediction accuracy, and this method will have a good application prospect in other biological experiments.
Enhanced Production of Tetramethylpyrazine in Bacillus licheniformis BL1 through aldC Over-expression and acetaldehyde Supplementation
Authors: Meng Wu , Ding Feng , Wang Rui-Ming , Wang Teng-Fei
Published: February 2020

Bacillus licheniformis BL1 was used as a starting strain to construct the recombinant tetramethylpyrazine (TMP)-producing strains by over-expression of the α-acetolactate decarboxylase gene (aldC) and α-acetolactate synthase gene (alsS), named BLC, BLS and BLCS, respectively. Then the addition of acetaldehyde was use to enhance the TMP yield in the fermentation process. During microaerobic fermentation, the aldC-overexpressed BLC strain produced 43.75 g TMP/L which was 15.47% higher than the TMP in culture yielded using the initial BL1 strain. Furthermore, the acetoin yield as TMP precursor similarly rose by 23.06% in BLC recombinant strain. In contrast, the 2,3-BD increased by 23.2% in the recombinant BLCS. TMP produced by BL1 could be bolstered via the supplementation of the acetaldehyde in fermentation medium. This method also has the same effect on the BLC strain.
Magnetic compass of garden warblers is not affected by oscillating magnetic fields applied to their eyes
Authors: Bojarinova Julia , Kavokin Kirill , Pakhomov Alexander , Cherbunin Roman , Anashina Anna , Erokhina Maria , Ershova Maria , Chernetsov Nikita
Published: February 2020

The magnetic compass is an important element of the avian navigation system, which allows migratory birds to solve complex tasks of moving between distant breeding and wintering locations. The photochemical magnetoreception in the eye is believed to be the primary biophysical mechanism behind the magnetic sense of birds. It was shown previously that birds were disoriented in presence of weak oscillating magnetic fields (OMF) with frequencies in the megahertz range. The OMF effect was considered to be a fingerprint of the photochemical magnetoreception in the eye. In this work, we used miniaturized portable magnetic coils attached to the bird’s head to specifically target the compass receptor. We performed behavioural experiments on orientation of long-distance migrants, garden warblers (Sylvia borin), in round arenas. The OMF with the amplitude of about 5 nT was applied locally to the birds’ eyes. Surprisingly, the birds were not disoriented and showed the seasonally appropriate migratory direction. On the contrary, the same birds placed in a homogeneous 5 nT OMF generated by large stationary coils showed clear disorientation. On the basis of these findings, we suggest that the disruption of magnetic orientation of birds by oscillating magnetic fields is not related to photochemical magnetoreceptors in their eyes.
Streptonigrin at low concentration promotes heterochromatin formation
Authors: Loyola Andre C. , Dao Kevin , Shang Robin , Zhang Lin , Dutta Pranabananda , Fowler Cody , Li Jinghong , Li Willis X.
Published: February 2020

Heterochromatin is essential for regulating global gene transcription and protecting genome stability, and may play a role in tumor suppression. Drugs promoting heterochromatin are potential cancer therapeutics but very few are known. In order to identify drugs that can promote heterochromatin, we used a cell-based method and screened NCI drug libraries consisting of oncology drugs and natural compounds. Since heterochromatin is originally defined as intensely stained chromatin in the nucleus, we estimated heterochromatin contents of cells treated with different drugs by quantifying the fluorescence intensity of nuclei stained with Hoechst DNA dye. We used HeLa cells and screened 231 FDA-approved oncology and natural substance drugs included in two NCI drug libraries representing a variety of chemical structures. Among these drugs, streptonigrin most prominently caused an increase in Hoechst-stained nuclear fluorescence intensity. We further show that streptonigrin treated cells exhibit compacted DNA foci in the nucleus that co-localize with Heterochromatin Protein 1 alpha (HP1α), and exhibit an increase in total levels of the heterochromatin mark, H3K9me3. Interestingly, we found that streptonigrin promotes heterochromatin at a concentration as low as one nanomolar, and at this concentration there were no detectable effects on cell proliferation or viability. Finally, in line with a previous report, we found that streptonigrin inhibits STAT3 phosphorylation, raising the possibility that non-canonical STAT function may contribute to the effects of streptonigrin on heterochromatin. These results suggest that, at low concentrations, streptonigrin may primarily enhance heterochromatin formation with little toxic effects on cells, and therefore might be a good candidate for epigenetic cancer therapy.
Comparative transcriptomics of the pheromone glands provides new insights into the differentiation of sex pheromone between two host populations of Chilo suppressalis
Authors: Guo Shuang , Tian Zhong , Quan Wei-Li , Sun Dan , Liu Wen , Wang Xiao-Ping
Published: February 2020

Reproductive isolation between different host populations is often based on intraspecific sex pheromone differences. The mechanisms underlying these differences have not been thoroughly elucidated to date. Previous studies suggested that Chilo suppressalis has differentiated into rice and water-oat host populations, and these two populations manifest clear differences in sex pheromone titer and mating rhythm. Hence, this moth is an ideal model to investigate the endogenous mechanisms of intraspecific reproductive isolation. Here, we identified a series of putative genes associated with sex pheromone biosynthesis based on the C. suppressalis pheromone gland transcriptome data. Transcripts of most genes were at higher level in the rice population. Then we obtained 11 pivotal differentially expressed genes (DEGs). The expression levels of these DEGs exhibited a distinct increase in the rice population. Moreover, we also observed the expression rhythm of these DEGs is discrepant between two host populations. Our study offers a new understanding to elucidate the mechanisms of intraspecific reproductive isolation.
Heritability of Inner Retinal Layer and Outer Retinal Layer Thickness: The Healthy Twin Study
Authors: Kong Mingui , Hwang Sungsoon , Ko Hyeonyoung , Song Yun-Mi , Ham Don-Il
Published: February 2020

The purpose of the study is to evaluate the heritability of inner retinal layer (IRL) and outer retinal layer (ORL) thicknesses in the healthy Korean population. This was a cross-sectional, twin and family study. We included 374 Korean adults with healthy eyes from 89 families. IRL thickness (from the internal limiting membrane to the external limiting membrane) and ORL thickness (from the external limiting membrane to the outer border of the retinal pigment epithelium layer) were measured in the nine macular subfields as defined by the Early Treatment of Diabetic Retinopathy Study using optical coherence tomography. The heritability on IRL and ORL thicknesses were investigated using a variance decomposition model. The heritability of IRL thickness was 0.87, 0.58, 0.85, 0.89, and 0.74 for the central, inner superior, inner inferior, inner temporal, inner nasal subfields, respectively; and 0.62, 0.83, 0.62, and 0.60 for the outer superior, outer inferior, outer temporal, outer nasal subfields, respectively. The heritability of ORL thickness was 0.56, 0.75, 0.66, 0.72, and 0.56 for the central, inner superior, inner inferior, inner temporal, inner nasal subfields, respectively; and 0.64, 0.63, 0.73, 0.54 for the outer superior, outer inferior, outer temporal, and outer nasal subfields, respectively. The heritability estimates of IRL thickness and ORL thickness ranged from moderate to high. The IRL thickness at the central, inner temporal, and inner inferior subfields had particularly high heritability.
Author Correction: Characterization of Sex-Based Dna Methylation Signatures in the Airways During Early Life
Authors: Nino Cesar L. , Perez Geovanny F. , Isaza Natalia , Gutierrez Maria J. , Gomez Jose L. , Nino Gustavo
Published: February 2020

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Market Assessment
Authors: Ladu L. , Wurster S.
Published: February 2020

Understanding consumer preferences with respect to sustainability is a key step toward the market uptake of biobased products. Within a European perspective, this chapter provides an overview of the results of a foresight activity aimed at identifying the demand for new sustainability criteria that are easily understood by different consumer groups (end consumers, businesses and public procurers) and relevant to their needs. Specific consideration is given to environmental, social and economic sustainability, which are together known as the three pillars of sustainability. Based on the presented research activities, eight conclusions could be drawn. The chapter finishes with implications for further research.
Indirect Land Use Change and Bio-based Products
Authors: Marazza D. , Merloni E. , Balugani E.
Published: February 2020

This chapter provides insights into those mechanisms leading to undesirable land use changes associated with the expansion of all biologically-based products, thus including biofuels and bio-based materials. The chapter conducts a reconnaissance of the land use change effects which are climate relevant, reversible in the long run or irreversible and, in some cases, synergetic with climate change. It reviews the main causes and presents evidence, as an example, of indirect land use changes – still ongoing – due to the biofuel policy in the US. The analysis of thresholds and certification criteria in the Renewable Energy Directive (RED II) revealed that a major role will be played by certification schemes and methods of certification of low iLUC risk biomass. Causal-descriptive models are presented as an appropriate class of models to support certification schemes and a dynamic system model generated through the European H2020 project STAR-ProBio project, named SydiLUC, is introduced. The model can be applied to various categories of bio-based products and estimates the annual land expansion per functional unit of bio-based product as well as the risk associated with a specific production route, in line with the most recent regulatory measures.
Synchrotron-based Mössbauer spectroscopy characterization of sublimated spin crossover molecules
Authors: Cini Alberto , Poggini Lorenzo , Chumakov Alexander I. , Rüffer Rudolf , Spina Gabriele , Wattiaux Alain , Duttine Mathieu , Gonidec Mathieu , Fittipaldi Maria , Rosa Patrick , Mannini Matteo
Published: February 2020

The spin crossover (SCO) efficiency of [57Fe(bpz)2(phen)] molecules deposited on gold substrates was investigated by means of synchrotron Mössbauer spectroscopy.
Aerobic photolysis of methylcobalamin: structural and electronic properties of the Cbl–O–O–CH3intermediate
Authors: Ghosh Arghya Pratim , Lodowski Piotr , Bazarganpour Aida , Leks Marzena , Kozlowski Pawel M.
Published: February 2020

Photolysis of methylcobalamin (MeCbl) in the presence of molecular oxygen (O2) has been investigated using density functional theory (DFT) and time-dependent DFT (TD-DFT).