bluuebunny/crossref_metadata_2025 huggingface dataset:
Variation in feral cat density between two large adjacent islands in Australia’s monsoon tropics
Authors: Davies Hugh F. , Rangers Tiwi Land , Rees Matthew W. , Stokeld Danielle , Miller Anna C. , Gillespie Graeme R. , Murphy Brett P.
Published: March 2021

Despite contributing to the ongoing collapse of native mammal populations across northern Australian savannas, we have limited understanding of the ecological constraints of feral cat population density in this system. Addressing such knowledge gaps is a crucial step towards mitigating the impacts of feral cats, and is particularly important for the large islands off northern Australia that remain as strongholds for numerous species vulnerable to cat predation. Here, we investigated cat density across Melville and Bathurst Island, two large islands in Australia’s monsoon tropics. We deployed large grids (~13 km2) of 70 camera-traps at four locations to investigate how feral cat density varies under different combinations of fire frequency, and feral herbivore presence. Using spatially-explicit capture-recapture models, we estimated feral cat density on Melville Island to be 0.15 cats km−2. We did not record any cat detections on Bathurst Island. Using simulations, we predicted that if cat density on Bathurst Island was equal to that on Melville Island, we would have expected to record 27.9 detections of 9.9 individual cats. Our results, coupled with other recent surveys, suggest that the density of cats is much lower on Bathurst Island than the adjacent Melville Island. The absence of feral herbivores on Bathurst Island may have contributed to this variation in cat density. Management that enhances understorey vegetation density, through feral herbivore control, as well as fire management, could help mitigate the impact of feral cats on northern Australian savanna biodiversity.
HflX is a GTPase that controls hypoxia-induced replication arrest in slow-growing mycobacteria
Authors: Ngan Jie Yin Grace , Pasunooti Swathi , Tse Wilford , Meng Wei , Ngan So Fong Cam , Jia Huan , Lin Jian Qing , Ng Sze Wai , Jaafa Muhammad Taufiq , Cho Su Lei Sharol , Lim Jieling , Koh Hui Qi Vanessa , Abdul Ghani Noradibah , Pethe Kevin , Sze Siu Kwan , Lescar Julien , Alonso Sylvie
Published: March 2021

Significance

GTPases play essential roles in living organisms, functioning as molecular switches or timers in many fundamental cellular processes. HflX is a GTPase that is highly conserved in the entire prokaryotic kingdom and is involved in the stress response of bacteria. We show here that under hypoxic stress, by modulating the cell’s translational activity, HflX controls mycobacteria growth rate and entry into nonreplicating state. Our work assigns a physiological role to HflX in pathogenic mycobacteria, implicating this factor in one of the most elusive but critical phenomena of replication arrest, which is responsible for the worldwide TB drug resistance crisis and a major roadblock to successful shorter TB therapies.
Trait similarity in reef fish faunas across the world’s oceans
Authors: McLean Matthew , Stuart-Smith Rick D. , Villéger Sébastien , Auber Arnaud , Edgar Graham J. , MacNeil M. Aaron , Loiseau Nicolas , Leprieur Fabien , Mouillot David
Published: March 2021

Significance

Biogeography has focused extensively on species identities, yet global patterns in species traits (morphological, physiological, or behavioral features) are not well known, including whether they are shaped by modern environmental conditions or by shared evolutionary history. Our global analysis of nearly 3,000 reef fish species found a consistent variety of traits across ocean basins worldwide, including a backbone of 21 trait combinations common to all oceans. At the regional scale, we found that fish assemblages in similar environments had similar trait compositions despite being separated by up to 100 degrees of latitude and hosting different species with distinct evolutionary histories. Thus, environmental conditions have likely shaped global patterns in reef fish traits regardless of geography, species identity, or evolutionary history.
Protein design-scapes generated by microfluidic DNA assembly elucidate domain coupling in the bacterial histidine kinase CpxA
Authors: Clark Iain C. , Mensa Bruk , Ochs Christopher J. , Schmidt Nathan W. , Mravic Marco , Quintana Francisco J. , DeGrado William F. , Abate Adam R.
Published: March 2021

Significance

DNA variant libraries allow unbiased analysis of sequence–function relationships. However, exhaustive combinatorial assemblies of even a modest number of parts produce libraries too large to practically screen. Library size can be reduced by manually blending parts to remove unwanted combinations, but this yields limited improvements and is difficult to scale. To address this challenge, we built a microfluidic hybrid valve–droplet device that selectively combines and assembles DNA parts into libraries of predefined composition with low bias. We use this system to construct and study a library of engineered histidine kinases, revealing how structural changes are communicated across adjacent domains to modulate kinase activity. Our method creates rationally reduced libraries and has applications in synthetic biology and protein engineering.
Electrochromic shift supports the membrane destabilization model of Tat-mediated transport and shows ion leakage during Sec transport
Authors: Asher Anthony H. , Theg Steven M.
Published: March 2021

Significance

Due to the transient nature of the active Tat complex, much of the knowledge available has been hard won. Electric-field-indicating absorbance transients allow investigation of transmembrane ion movement using native electric potential in thylakoids while circumventing challenges of reconstitution. Electrical behavior of transiently and/or constitutively assembled complexes suggests that Sec translocation occurs through a barrel-stave-type proteinaceous pore, while Tat translocation likely occurs through a toroidal pore. This would be the first instance of toroidal pores being exploited by a general protein translocation system. Our electrochemical analysis offers insight into how protein transport might be linked to light stimulation. Localized membrane destabilization presents a rational link between the proton motive force, membrane thinning, and Tat-mediated transport of substrates critical to photosynthesis.
Type III secretion system effector proteins are mechanically labile
Authors: LeBlanc Marc-André , Fink Morgan R. , Perkins Thomas T. , Sousa Marcelo C.
Published: March 2021

Significance

The type III secretion system (T3SS) is an important virulence factor that enables some bacteria to directly inject effector proteins into host cells, facilitating colonization. To be secreted, effector proteins must be unfolded, and tightly packed proteins like GFP cannot be secreted through the T3SS, leading to the model that effector proteins have low thermodynamic stability. We show that two model effector proteins have thermodynamic stabilities similar to tightly packed proteins (GFP and ubiquitin) but are much more mechanically labile. These results strongly suggest that mechanical stability predicts whether a protein is compatible with secretion through the T3SS and may shed light on the distinct evolutionary pressures that resulted in the sequence divergence of effector proteins from their nonsecreted homologues.
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

Significance

Motivated 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

Significance

Attention 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

Significance

Virtually 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

Significance

Using 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

Significance

Meiotic 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

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

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

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

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

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.
Straightening up is required to nucleate new microtubules
Authors: Gardner Melissa K.
Published: March 2021

In this issue, Ayukawa, Iwata, Imai, and colleagues (2021. J. Cell Biol.https://doi.org/10.1083/jcb.202007033) use rapid temporal and high-spatial-resolution electron microscopy imaging to examine the earliest stages of new microtubule nucleation. They discover that straightening of curved tubulin oligomers increases the efficiency of microtubule nucleation.
The role of molecular diffusion within dendritic spines in synaptic function
Authors: Obashi Kazuki , Taraska Justin W. , Okabe Shigeo
Published: March 2021

Spines are tiny nanoscale protrusions from dendrites of neurons. In the cortex and hippocampus, most of the excitatory postsynaptic sites reside in spines. The bulbous spine head is connected to the dendritic shaft by a thin membranous neck. Because the neck is narrow, spine heads are thought to function as biochemically independent signaling compartments. Thus, dynamic changes in the composition, distribution, mobility, conformations, and signaling properties of molecules contained within spines can account for much of the molecular basis of postsynaptic function and regulation. A major factor in controlling these changes is the diffusional properties of proteins within this small compartment. Advances in measurement techniques using fluorescence microscopy now make it possible to measure molecular diffusion within single dendritic spines directly. Here, we review the regulatory mechanisms of diffusion in spines by local intra-spine architecture and discuss their implications for neuronal signaling and synaptic plasticity.
The Cranefield Awards
Authors: Eisner David A.
Published: March 2021

Update from the Editor-in-Chief
Two-dimensional flow and linear stability properties of smectic A liquid crystals
Authors: Snow B C , Stewart I W
Published: March 2021

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

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

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

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

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

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

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−.
Production of dual species Bose–Einstein condensates of 39K and 87Rb*
Authors: Mi Cheng-Dong , Nawaz Khan Sadiq , Wang Peng-Jun , Chen Liang-Chao , Meng Zeng-Ming , Huang Lianghui , Zhang Jing
Published: March 2021

We report the production of 39K and 87Rb Bose–Einstein condensates (BECs) in the lowest hyperfine states | F = 1,mF
= 1 〉 simultaneously. We collect atoms in bright/dark magneto-optical traps (MOTs) of 39K/87Rb to overcome the light-assisted losses of 39K atoms. Gray molasses cooling on the D1 line of the 39K is used to effectively increase the phase density, which improves the loading efficiency of 39K into the quadrupole magnetic trap. Simultaneously, the normal molasses is employed for 87Rb. After the microwave evaporation cooling on 87Rb in the optically plugged magnetic trap, the atoms mixture is transferred to a crossed optical dipole trap, where the collisional properties of the two species in different combinations of the hyperfine states are studied. The dual species BECs of 39K and 87Rb are obtained by further evaporative cooling in an optical dipole trap at a magnetic field of 372.6 G with the background repulsive interspecies scattering length a
KRb = 34 a
0 (a
0 is the Bohr radius) and the intraspecies scattering length a
K = 20.05a
0.
Errors in solving math problems based on newman type
Authors: Eko Subekti Fitrianto , Puspita Sari Desy
Published: March 2021

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.
Mathematical word problem solving abilities of hearing-impaired students
Authors: Suarsana I M , Sudatha I G W , Mahayukti G A , Apsari R A
Published: March 2021

One of the useful methods to facilitate the students in understanding the benefits and real application of mathematics in real life is by formulating the problem in words. Unfortunately, the previous studies found that students with hearing difficulties usually have limited vocabularies and it becomes a barrier to them in understanding the given context in word problems. Therefore, this study aims at describing the ability of students with hearing-impaired problem in solving mathematical word problems by examining the mathematical skills performed. Since the purpose is to describe a phenomenon, qualitative approach with case study design was deliberately chosen as the method of the study. The subject of the research was eight seventh grade students of School for the Hearing-Impaired in Singaraja, Bali-Indonesia. The data were collected through written test and interview. Afterwards, the data were analysed qualitatively using descriptive method. The results show that the students with hearing-impaired problem were struggling in solving mathematical word problems due to the lack of understanding of the problem and mathematical concepts. Furthermore, there is no tendency for the students with lower level of hearing difficulties to perform better in solving word problems.
The existence of irregular n-shape containing a unit circle based on MATLAB
Authors: Utomo Beni
Published: March 2021

This research will provide an implementation of the study about the area in terms of numerical point of view. Regular n-shaped constructions that load a unit circle and load in unit circles can be made for at least 3 points on the unit circle. The irregular n-shaped construction contained in the unit circle can also be made without conditions with a minimum of 3 points on the unit circle. The problem arises in the irregular n-shaped construction that contains the unit circle, apparently it cannot be made by taking 3 points freely. The purpose of this research is to conduct an analysis related to what conditions are needed so that the irregular n terms can be made so that it contains a unit circle. The method used is a literature review, carried out by comparing and analyzing research that has been done relating to irregular and irregular aspects, the analysis process is carried out on irregular n-construction construction with the help of MATLAB for visualization. The results of the research show that one of the requirements for irregular n-terms can be made and contain unit circles found, and the theory test is carried out empirically with the help of MATLAB for visualization. Another result is a theory about the existence of the irregular n-aspect mathematically.
Mathematical disposition of strategic thinking ability in working on HOTS questions
Authors: Firmansyah E , Mubarika M P , Saniah L
Published: March 2021

This article contains the results of a study of the mathematical disposition of strategic thinking skills in working on HOTS (High Order Thinking Skills) questions. HOTS’s problem in learning mathematics has recently become a trend. Therefore, many educators have begun to learn about the characteristics of HOTS questions, and some of them consider HOTS problems to be closely related to problems with a high degree of difficulty. This study was made with the aim of looking at the relationship between mathematical dispositions and the ability to think strategically in working on HOTS questions. In learning mathematics, it is suspected that the mathematical disposition has an important role in solving HOTS problems with the assumption that if a student has a good mathematical disposition then he can do HOTS problems easily. Working on HOTS questions is also closely related to the ability to think strategically because the characteristics of HOTS questions require students to think strategically in solving existing problems. The ability to think strategically, basically run by personal characteristics, one of which is mathematical disposition. Therefore, mathematical disposition has an important role in the ability to think strategically in working on HOTS problems.
ICT literacy level of Indonesian senior high school mathematics teachers
Authors: Nugroho Yanuarto Wanda , Mistima Maat Siti , Husnin Hazrati
Published: March 2021

Industrial revolution 4.0 nowadays needs I CT literacy to proceed with the technology used for mathematics teachers. Meanwhile, the ICT literacy of mathematics teachers in Indonesia is at a low level and under the other Asia countries. This article aims to look at the level category of ICT literacy among Indonesian Mathematics Teachers in Senior School background. The researcher employed a quantitative approach in the term of descriptive statistical measurement. The collected data were used in order to determine descriptive statistical analysis for each construct; then followed by measuring the mean score, frequently, and finally, interpretation into each construct was applied; in order to set the level of ICT literacy using Dakich category level. This study used the ICT literacy questionnaire consists of 21 items in the form of a 5-point Likert scale. The results show that the level of understanding of the operation and use of ICT, ICT-rich pedagogy, ICT for teaching and professional involvement, and social ecology of ICT life and teaching and as a whole is in the category of access to ICT. This level implied that ICT literacy as a combination of intellectual ability, basic concepts, and new skills possessed by teachers to navigate and use information and communication technology effectively. Also, the level of ICT literacy is based on technical literacy and information literacy, which contains technical questions and information processing skills questions in accessing ICT for teachers. This study contributes to the ICT literacy level, which provides views to mathematics teachers to improve the quality of teachers’ ICT literacy in teaching mathematics.
Identifying geometrical objects in Sumur Gumuling Tamansari: An ethnomathematics analysis
Authors: Nur Alvian Davet , Agustito Denik , Astuti Arigiyati Tri , Harini Esti , Adi Widodo Sri
Published: March 2021

This research was conducted to find mathematical elements (ethnomathematics) in the Sumur Gumuling Tamansari building. The research method used in this study is a qualitative method with an ethnographic approach. The data used are data obtained from observations, documentation, and interviews. Observation and documentation are used to identify ethnomathematics in the Sumur Gumuling Tamansari building. While documentation and interviews with the triangulation method to find out more deeply the cultural values that exist in the Sumur Gumuling Tamansari building. The results of this study are there are mathematical elements (ethnomathematics) in the Sumur Gumuling Tamansari building, namely the concept of a rectangle, pentagon, rhombus, triangle, circle, and the combined concept of a rectangular flat structure with a half-circle. In this case, it can be said that mathematics enters a ll aspects of life including cultural buildings.
The use of technology in learning geometry
Authors: Lu’luilmaknun U , Salsabila N H , Triutami T W , Novitasari D , Junaidi
Published: March 2021

Geometry is important material in mathematics, but some students still find it difficult to learn geometry. The teacher used technology to make it easier for students to learn geometry. The aim of this study is to describe the perception of junior high school students on technology in geometry learning. This type of study is a survey study. The population of study were 100 junior high school students in MTsN 1 Mataram, NTB, Indonesia. The data were taken from 3 to 4 December 2019. The data were collected by questionnaire. Data were analysed using quantitative descriptive methods. The results showed that most students were able to utilize technology in their daily lives. There are 57% of students who have experience learning geometry with technology. There are 67% of students utilizing technological devices for learning geometry and 66% of the devices students often use are smartphones. There are 56% of students who use learning technology such as a learning video. The data also shows that most students agree that learning geometry with technology can have a positive effect on geometry learning. From the results, teachers can also use technology more often to make it easier for students to learn geometry.
Reviving the role of mathematics in science through STEM
Authors: Jazuli Akhmad
Published: March 2021

The STEM learning presented here is designed to facilitate the students to possess skills of imagination, collaboration, problem-solving, as well as critical and creative thinking which highly needed in this rapidly changing era. STEM learning aims to combine science, technology, engineering and mathematics by means of connections between subjects and real-world problems. In the empirical facts, however, STEM has only been practiced in natural science, and has not yet been applied to social science. This literature review analyzes the role of mathematics in developing science, both natural science and social science. In conclusion, mathematics can be played as a role in the development of science, both natural science and social science with various conditions.
Mathematic teachers’ perception on the use of moodle based learning management system in teaching mathematic during the time of covid 19
Authors: Ahmad  , Eko Subekti Fitrianto
Published: March 2021

The aim of the study was to find out the Mathematic Teachers’ perception on the use of Moodle based learning management system in teaching mathematic during the time of Covid 19. The mix methods research design using quantitative and qualitative was used as the method of this research. Fifty six mathematic teachers from elementary to high school in Banyumas Regency were used as the respondents of this research. The questionnaire, semi structure interview and documents were used as a data collection method. Descriptive statistic and thematic data analysis was used as the technique in analyzing the data. The result showed that more than 40% teachers agree if Moodle facilities are very good or by the school and more than 60% teachers agree if the use of Moodle has positive impact to Mathematic learning. This research also got the result if teachers have negative perception on readiness of resources in using Moodle with more than 30% disagree if teachers are ready enough to use Moodle.
Potential solving mathematical problem students focused on self-directed learning in COVID-19 pandemic
Authors: Muhammad Malim , Purwanto Joko , Abida Rahmania
Published: March 2021

The purpose of this research was to depict the mathematical skill of high-school 1 Jeruklegi, 7th-grade students, who have been examined by their teaching in Cilacap Indonesia. This research was a descriptive qualitative analysis. The outcomes of self-directed learning problems, tests on mathematical problem resolution, and interviews collected the data from this research. The data use a method of triangulation. Students were divided into three classes based on the questionnaire’s findings, namely students in the high, medium, and low self-directed learning categories. A purposive sampling technique was used to determine the research subjects. Data from the test and interview were used to identify the mathematical problem-solving abilities of the students. The results of this study show that students with the high self-directed learning group were able to fulfill the indicators of understanding the problem, compile a solution plan, do calculations according to the plan, and check the results obtained. However, the respondents were only able to fulfill the indicators of understanding the problem in the medium self-directed learning category, compile a plan for completion, and do calculations according to the plan. Meanwhile, in the low self-directed learning category, respondents were capable of following the standards to complete the steps to understand the issue and formulate a response plan
Low Noise Amplifier Design and Performance Analysis of RF Front-End for Narrow Band Receivers
Authors: Divya Amgothu Laxmi , Mudavath Mahesh , Ranadheer Ch S , Afzal Mohamed , Venkateswarlu R.
Published: March 2021

This manuscript presents the low noise amplifier design and performance analysis of receiver RF front-end for narrowband wireless communications. The LNA is a central building block of the wireless receiver. A single-ended cascode CMOS LNA is purposeful for reconfigurable applications such as Wireless LAN. The scope of this manuscript is to design an LNA appropriate for wireless applications with improved performance metrics. The contributions of this paper are noise reduction and high gain using an inductive degeneration common source stage. The proposed LNA espouses the entire simulation results in the frequency band of 2.44GHz. The excellent Noise Figure obtained as 0.95dB; the preferable power gain (S21) is 17dB, also the results of P-1dB of -17.3dBm, IIP3 of -10.7dBm at 2.44GHz, respectively. However, the perfect input and output matching network is achieved with proper reverse shielding and excellent stability.