bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sortase-assembled pili in
Corynebacterium diphtheriae
are built using a latch mechanism
Authors: McConnell Scott A. , McAllister Rachel A. , Amer Brendan R. , Mahoney Brendan J. , Sue Christopher K. , Chang Chungyu , Ton-That Hung , Clubb Robert T. 
Published: March 2021

Significance
Bacteria display hair-like structures called pili that enable them to adhere to host tissues, surfaces, and other bacteria. Understanding how microbes assemble and display pili is important, as these structures play a key role in host–pathogen interactions that cause disease. In this study, we have gained insight into how pathogenic Gram-positive bacteria assemble pili by visualizing the intersubunit covalent crosslink that stabilizes these fibrous structures and by investigating how pili are assembled by specialized pilus-specific sortase enzymes. We propose that pili are assembled via a conserved “latch” mechanism that is critical for driving the crosslinking of specific sites on the pilus.
Point configurations, phylogenetic trees, and dissimilarity vectors
Authors: Caminata Alessio , Giansiracusa Noah , Moon Han-Bom , Schaffler Luca 
Published: March 2021

SignificanceMotivated by the desire to estimate phylogenetic trees from data on collections of taxa rather than just pairs, in 2004 a new variant of phylogenetic tree reconstruction was introduced, and two important theoretical questions were asked about it. One of these questions was solved within a few years; the other remained open until now. We resolve this second question and in doing so significantly enlarge a bridge between phylogenetics and a rapidly developing area of contemporary mathematics called tropical geometry.
Directed information exchange between cortical layers in macaque V1 and V4 and its modulation by selective attention
Authors: Ferro Demetrio , van Kempen Jochem , Boyd Michael , Panzeri Stefano , Thiele Alexander 
Published: March 2021

SignificanceAttention is thought to modulate sensory processing by changing communication between cortical areas within specific frequency bands. Using local field potential recordings, we tested this influential model through laminar recordings in macaque V1 and V4. Attention modulated communication unexpectedly. In V1, it decreased communication across spectral frequencies except for granular-to-supragranular interactions. In V4, it increased communication across all spectral frequencies. Critically, attention increased V1–V4 feedforward communication across all frequency bands, decreased V4–V1 feedback communication in low-frequency bands, and increased beta and gamma feedback communication. These findings challenge existing theories of frequency specificity of feedforward and feedback interactions.
A co-opted steroid synthesis gene, maintained in sorghum but not maize, is associated with a divergence in leaf wax chemistry
Authors: Busta Lucas , Schmitz Elizabeth , Kosma Dylan K. , Schnable James C. , Cahoon Edgar B. 
Published: March 2021

SignificanceVirtually all above-ground plant surfaces, such as leaf and stem exteriors, are covered in a cuticle: a wax-infused polyester. This waxy biocomposite is the largest interface between Earth’s biosphere and atmosphere. Its chemical composition is not only highly tuned to mediate nonstomatal water loss, but it also self-assembles to produce superhydrophobic surfaces, protects against UV radiation, and contains bioactive compounds that help resist microbial attack. Developing fundamental knowledge of waxy biocomposites, particularly those on crop species, is a prerequisite for an understanding of their structure–function relationships. Here, we uncover a likely genetic basis for the presence and absence, respectively, of triterpenoids in the leaf waxes of sorghum and maize—compounds previously associated with creating heat-tolerant cuticular water barriers.
Chemical pumps and flexible sheets spontaneously form self-regulating oscillators in solution
Authors: Manna Raj Kumar , Shklyaev Oleg E. , Balazs Anna C. 
Published: March 2021

SignificanceUsing computational modeling, we designed a self-oscillating materials system that is driven by a nonperiodic chemical reaction to undergo both periodic shape changes and motion. Catalytic reactions in a fluid-filled microchamber drive the movement of the fluid and immersed flexible sheets. The fluid affects the sheets' shape, and the sheets affect the fluid flow. This feedback enables remarkably rich and controllable oscillatory behavior: a single sheet fishtails periodically across the chamber or circulates continuously within a narrow region. Two sheets form coupled oscillators displaying not only synchronized temporal behavior, but also unique, coordinated morphological reconfigurations. These oscillators enable development of soft robots that operate through an inherent coupling of chemistry and motion, permitting novel autonomous and self-regulating behavior.
Structural basis for selective AMPylation of Rac-subfamily GTPases by
Bartonella
effector protein 1 (Bep1)
Authors: Dietz Nikolaus , Huber Markus , Sorg Isabel , Goepfert Arnaud , Harms Alexander , Schirmer Tilman , Dehio Christoph 
Published: March 2021

Significance
Mammalian cells regulate diverse cellular processes in response to extracellular cues. Small GTPases of the Rho family act as molecular switches to rapidly regulate discrete cellular activities, such as cytoskeletal dynamics, cell movement, and innate immune responses. Numerous bacterial virulence factors modulate the function of Rho-family GTPases and thereby manipulate intracellular signaling. For many of these virulence factors we have gained detailed understanding how they covalently modify individual Rho-family GTPases to reprogram their activities; however, their mechanisms of selective targeting of distinct subsets of Rho-family GTPases remained elusive. Using a combination of structural biology and biochemistry, we demonstrate for the effector protein Bep1 exclusive specificity for Rac-subfamily GTPases and propose the underlying mechanism of target selectivity.
The synaptonemal complex imposes crossover interference and heterochiasmy inArabidopsis
Authors: Capilla-Pérez Laia , Durand Stéphanie , Hurel Aurélie , Lian Qichao , Chambon Aurélie , Taochy Christelle , Solier Victor , Grelon Mathilde , Mercier Raphael 
Published: March 2021

SignificanceMeiotic recombination promotes genetic diversity by shuffling parental chromosomes. As observed by the very first geneticists, crossovers inhibit the formation of another crossover nearby, an elusive phenomenon called crossover interference. Another intriguing observation is heterochiasmy, the marked difference in male and female crossover rates observed in many species. Here, we show that the synaptonemal complex, a structure that zips homologous chromosomes together during meiosis, is essential for crossover interference inArabidopsis. This suggests that a signal that inhibits crossover formation nearby a first crossover propagates along this specific structure. Furthermore, in the absence of the synaptonemal complex, crossover frequencies become identical in both sexes, suggesting that heterochiasmy is due to variation of crossover interference imposed by the synaptonemal complex.
The cyanobacterial taxis protein HmpF regulates type IV pilus activity in response to light
Authors: Harwood Thomas V. , Zuniga Esthefani G. , Kweon HoJun , Risser Douglas D. 
Published: March 2021

Significance
Many photosynthetic cyanobacteria are capable of migrating in response to light in a process known as phototaxis. In all of the cyanobacteria where this process has been characterized at the genetic and molecular level, motility has been shown to be powered by type IV pili and influenced by chemotaxis-like systems with methyl-accepting chemotaxis proteins containing light-sensing GAF domains. However, the means by which the light-sensing systems modulate T4P activity has not been defined. In this study we provide evidence that cyanobacteria possess a second, distinct system for sensing light, the Hmp chemotaxis-like system, which lacks a GAF domain and modulates direct interaction between the cyanobacterial taxis protein HmpF and the T4P to regulate motility in response to light.
The impact of teaching approach on growth in L2 proficiency and self-efficacy
Authors: Harris Justin , Leeming Paul 
Published: March 2021

Abstract
Despite the increasing popularity of task-based language teaching (TBLT) among researchers and teachers, further
classroom-based empirical evidence is needed to support its use over more traditional teaching approaches such as
presentation practice production (PPP). The argument that TBLT is ‘legislation by hypothesis’ (Swan, 2005), is yet to be completely refuted (Ellis, 2018). Four intact classes of Japanese university students
taking a one-year oral English course were randomly assigned to either a TBLT or PPP teaching condition. Speaking proficiency and
speaking self-efficacy were measured three times during the year to discover the differential impact of teaching approach on
growth. Student interviews provided insights into their views on the different approaches. Results showed that students in TBLT
and PPP classes experienced growth in both proficiency and self-efficacy, and there was no difference in final outcomes for the
two conditions. However, patterns of growth for the groups were different.
Diachronic register change
Authors: Collins Peter , Korhonen Minna , Kotze Haidee , Smith Adam , Yao Xinyue 
Published: March 2021

Abstract
A number of studies have found that grammatical differences across registers are more extensive than those across
dialects. However, there is a paucity of research examining intervarietal register change, exploring how registers change
differently over time in different regional varieties. The present study addresses this diachronic deficit, focusing on
grammatical developments – from the early 20th to the early 21st century – in corpora representing three written
registers and two speech-based registers in Australian, British and American English. We conducted a factor analysis on 68
lexicogrammatical features to identify six dimensions of register variation, and subsequently investigated the diachronic change
of the five registers across these dimensions. We interpret our findings in terms of the differential effects of broad social
changes on individual registers, in light of existing findings on trends of change in different registers and varieties.
Exploring the relationship between TBLT and ISLA
Authors: Loewen Shawn , Sato Masatoshi 
Published: March 2021

Abstract
The relationship between task-based language teaching (TBLT) and instructed second language acquisition (ISLA) is a close
one. Both are concerned primarily with facilitating the development of second language (L2) learners’ linguistic proficiency. This article
begins by providing a brief description of both terms. TBLT has been described as an approach to language teaching, comprised primarily of a
needs analysis, development of meaning-focused instructional materials, and assessment. The central construct is the task, which provides
opportunities for learners to use their own linguistic resources as they engage in meaning-focused interaction. In contrast, ISLA is a research field encompassing multiple approaches to L2 teaching and learning, based on various theoretical perspectives. As such, ISLA includes TBLT,
especially as both have a particular interest in the cognitive-interactionist approach to L2 instruction. Differences between the two terms
include a focus on explicit instruction in ISLA that is not present in most versions of TBLT. In addition, ISLA does not constitute an
all-encompassing curricular approach to L2 instruction. Finally, ISLA has been less focused on needs analyses and assessment in comparison
to TBLT. This article ends with a consideration of areas of mutual concern, as well as perspectives from each that might benefit the
other.
The phonetics of Namibian English
Authors: Schröder Anne , Zähres Frederic , Kautzsch Alexander 
Published: March 2021

Abstract
Namibian English (NamE) is frequently referred to
as an offspring of (White) South African English (SAfrE), although
more recently researchers have tried to describe it as a variety in
its own right. In particular, Kautzsch and Schröder (2016) describe several phonetic
features seemingly specific to NamE and unattested in other (South)
African Englishes. This paper takes up some of their findings and
provides further evidence for Namibian-specific realisations of
vowels by investigating a supposedly NamE-specific
nurse–work split and comparing realisations of
the trap–dress merger attested in some varieties
of SAfrE. The paper supports the claim that NamE should be considered
a variety in its own right, further demonstrating that it
should not be seen as a monolithic whole.
A land in transition
Authors: Schröder Anne 
Published: March 2021

Abstract
This chapter looks at linguistic diversity as
represented in two Namibian novels, discussing aspects of
authenticity, identity formation, style-shifting, and meta-language,
but also the representation of multilingualism in literary texts. By
combining linguistic analysis with literary study, the chapter sheds
light on questions of language ideology and the representation of
language groups, some marginalized, in the multi-lingual and
multi-cultural make-up of the Namibian nation at its beginning and
during the first years of its existence. This will help to gain some
insights into the construction of ‘Namibianness’ during the struggle
for and the first years after independence.
Two-dimensional flow and linear stability properties of smectic A liquid crystals
Authors: Snow B C , Stewart I W 
Published: March 2021

Abstract
We examine some leading-order flow and stability properties of smectic A (SmA) liquid crystals (LCs) in two spatial dimensions by analysing a fully nonlinear continuum theory of these materials. We derive a system of equations for the dynamic variables describing the flow velocity and orientation of the material under suitable assumptions upon these quantities. This system can provide insight into the leading-order behaviour under quite general circumstances, and we provide an example of utilising this system to determine the flow induced by a constant pressure gradient applied normally to the smectic layers. We then consider the effect of oscillatory perturbations on a relaxed, stationary sample of SmA, and provide criteria under which one would expect to see the onset of instability in the form of inequalities between the material parameters and perturbative wave number. We find that instability occurs for physically realisable values of these quantities, and, in particular, that certain viscosities characterising the SmA phase can act as ‘destabilising agents’ such that one could, for a given sample with known parameter values, manipulate the behaviour of that sample.
An effective health indicator for the Pelton wheel using a Levy flight mutated genetic algorithm
Authors: Vashishtha Govind , Kumar Rajesh 
Published: March 2021

Abstract
Fluctuations in the head, discharge, and contaminants in the flow can damage parts of the Pelton wheel. An artificial intelligence technique has been investigated for the automatic detection of bucket faults in the Pelton wheel. Features sensitive to defect conditions are extracted from the raw vibration signal and its variational mode decomposition (VMD). The issue of slow convergence speed of the genetic algorithm during optimization is duly addressed by implementing a Levy flight mutated genetic algorithm (LFMGA) while finding the optimal parameters (regularization parameter and kernel function) of a support vector machine (SVM). The efficacy of the proposed LFMGA is tested against different optimization benchmark functions. The results indicate that the proposed algorithm is stable on the basis of the small standard deviation. Using optimized SVM parameters, the SVM model is trained to prepare a classification model with 10-fold cross-validation. After training, the SVM model is tested for fitness evaluation. The overall recognition rate of the SVM model for identification of defects is found to be 98.84% with training time 27.06 s per iteration. A healthy condition is also compared with splitter wear, added mass defect, and missing bucket conditions separately using the VMD–SVM model and shows a recognition rate of 99.17%, 98.33%, and 98.12%, respectively.
One-dimensional nitrogen doped porous carbon nano-array arranged by carbon nanotubes for electrochemical sensing ascorbic acid, dopamine and uric acid simultaneously
Authors: Wu Fang-Hui , Ren Mei-Juan , Wang Miao , Sun Wen-Bin , Wu Kong-Lin , Cheng Yuan-Sheng , Yan Zhengquan 
Published: March 2021

Abstract
In this work, one-dimensional nitrogen doped porous carbon nano-arrays arranged by carbon nanotube (1D CNTs@NPC) were first constructed, using a coating technology at room temperature and followed by high temperature carbonization. It was expected that the resulting glassy carbon electrodes modified by 1D CNTs@NPC (CNTs@NPC/GCE) could express different electrochemical responses to ascorbic acid (AA), dopamine (DA), uric acid (UA), by virtue of the synergistic-improved effect between CNTs and NPC. Under the optimized conditions, there were excellent analytical parameters for CNTs@NPC/GCE to detect AA, DA and UA, i.e. a wide linear range of 40–2100 μM for AA, 0.5–49 μM for DA and 3–50 μM for AA with low detection limits of 0.36 μM, 0.02 μmol l−1 and 0.57 μM respectively. Importantly, the proposed CNTs@NPC/GCE was efficiently applied to determine AA, DA and UA in some real samples with high stability, reproducibility and selectivity. This work will offer an efficient potential for diagnosing ascorbic acid, dopamine or uric acid-related diseases on clinical testing in future.
Boron, and nitrogen co-doped carbon dots as a multiplexing probe for sensing of p-nitrophenol, Fe (III), and temperature
Authors: Tummala Srikrishna , Lee Chia-Hung , Ho Yen-Peng 
Published: March 2021

Abstract
Boron and nitrogen co-doped carbon dots (B, N-CDs) were fabricated through a simple, one-step hydrothermal reaction of citric acid, boric acid, and tris base. The obtained B, N-CDs exhibit excitation-dependent fluorescence, high quantum yield (QY), biocompatibility, photostability, and aqueous solubility. The QY was substantially increased to 57% by doping boron atoms. Furthermore, the fluorescence intensity of B, N-CDs was temperature-dependent and decreased linearly from 283 to 333 K. The prepared B, N-CDs were used as a fluorescence probe for the detection of para-nitrophenol (p-NP) and Fe (III) ions with low detection limits of 0.17 μM and 0.30 μM, respectively. Moreover, the presence of p-NP could be further confirmed by a colorimetric assay. The fluorescent probe has been applied to determine p-NP and Fe (III) in a spiked serum sample and spiked water samples (lake and tap water). Moreover, the as-prepared B, N-CDs were of low toxicity and capable of bioimaging.
Optical polarization of light emission from sidewalls of single quantum well near interface in spontaneous regime
Authors: Sarelli Eirini , Pillet Jean Christophe , Ben Bakir Badhise , Le Blevennec Gilles 
Published: March 2021

Abstract
Color conversion is necessary in the case of blue light emitting diodes (LEDs) in the field of display applications. One of the most common strategies consists of colloidal emitter quantum dots (QDs) pumped by a GaN based LED. To improve the coupling between the active LED area and the QDs, the authors investigated the particular case of the near field coupling by placing the LED quantum wells (QWs) near its surface. This coupling strongly depends on the dipole orientation. We report results on the polarized light emission from the sidewall of an LED. More precisely, we studied a single QW InGaN structure, located at a few nanometers from the LED’s surface. Dies were placed under a confocal microscope with the sidewall perpendicular to the optical axis. A rotational polarizer was used to analyze the emitted light. This experiment allows determining the polarization of the spontaneous emission. Experimental results demonstrate the strong impact of the surface proximity on the polarization of emitted light.
Characterization of extragalactic point-sources on E- and B-mode maps of the CMB polarization
Authors: Diego-Palazuelos P. , Vielva P. , Herranz D. 
Published: March 2021

Abstract
Although interesting in themselves, extragalactic sources emitting in the microwave range (mainly radio-loud active galactic nuclei and dusty galaxies) are also considered a contaminant from the point of view of Cosmic Microwave Background (CMB) experiments. These sources appear as unresolved point-like objects in CMB measurements because of the limited resolution of CMB experiments. Amongst other issues, point-like sources are known to obstruct the reconstruction of the lensing potential, and can hinder the detection of the Primordial Gravitational Wave Background for low values of r. Therefore, extragalactic point-source detection and subtraction is a fundamental part of the component separation process necessary to achieve some of the science goals set for the next generation of CMB experiments. As a previous step to their removal, in this work we present a new filter based on steerable wavelets that allows the characterization of the emission of these extragalactic sources. Instead of the usual approach of working in polarization maps of the Stokes' Q and U parameters, the proposed filter operates on E- and B-mode polarization maps. In this way, it benefits from the lower intensity that, both, the CMB, and the galactic foreground emission, present in B-modes to improve its performance. To demonstrate its potential, we have applied the filter to simulations of the future PICO satellite, and we predict that, for the regions of fainter galactic foreground emission in the 30 GHz and 155 GHz bands of PICO, our filter will be able to characterize sources down to a minimum polarization intensity of, respectively, 125 pK and 14 pK. Adopting a Π=0.02 polarization degree, these values correspond to 169 mJy and 288 mJy intensities.
Chiral effective Lagrangian for excited heavy-light mesons from QCD
Authors: Chen Qing-Sen , Fu Hui-Feng , Ma Yong-Liang , Wang Qing 
Published: March 2021

Abstract
We derive the chiral effective Lagrangian for excited heavy-light mesons from QCD under proper approximations. We focus on the chiral partners with

j

l

P

=

3

2

+

and

j

l

P

=

3

2

−

which amounts to (1+, 2+) and (1−, 2−) states respectively. The low energy constants including the masses of the chiral partners are calculated. The calculated spectrum for the excited mesons are found roughly consistent with experimental data. In addition, our results indicate that quantum numbers of B

J
(5970) can be identified with 1− or 2−.
Errors in solving math problems based on newman type
Authors: Eko Subekti Fitrianto , Puspita Sari Desy 
Published: March 2021

Abstract
The research aims to identify the types of mistakes students make in solving math problems in straight-line equation materials based on Newman type. The study subjects were 34 students of Grade VIII G SMP Negeri 2 Baturraden. Data retrieval techniques using tests. The data is analyzed with the Newman stage. The results showed 1) the highest percentage of errors on question number two was 93.08%; 2) the highest percentage of student errors at the encoding stage of 69.16%; and the lowest at the Transformation stage of 53.36%; 3) some of the mistakes made include: errors in understanding the problem, inaccuracies placing symbols in the problem-solving process, do not write down the complete information on the question; do not use formulas correctly, do not use proper calculation procedures, and did not write the final result correctly because students were still mistaken in doing calculations.