bluuebunny/crossref_metadata_2025_split huggingface dataset:
Understanding the influence of lipid bilayers and ligand molecules in determining the conformational dynamics of somatostatin receptor 2
Authors: Nagarajan Santhosh Kumar , Babu Sathya , Kulkarni Seema A. , Vadivelu Aanand , Devaraju Panneer , Sohn Honglae , Madhavan Thirumurthy 
Published: April 2021

AbstractSomatostatin receptor 2 (SSTR2) is a G-protein coupled receptor (GPCR) that controls numerous cellular processes including cell-to-cell signaling. In this study, we report how the lipid and ligand molecules influence the conformational dynamics of the membrane-bound SSTR2. Molecular simulations of different holo and apoenzyme complexes of SSTR2 in the presence and absence of a lipid bilayer were performed, observed, and correlated with previously reported studies. We identified the important SSTR2 residues that take part in the formation of the SSTR2-ligand complex. On analyzing the molecular simulation trajectories, we identified that the residue D3.32 is crucial in determining the bioactive conformation of SSTR2 ligands in the binding site. Based on the results, we suggest that designing a novel SSTR2 ligand with an H-bond donor group at the R1 position, and hydrophobic groups at R2 and R3 might have higher activity and SSTR2-selectivity. We analyzed the simulated systems to identify other important structural features involved in SSTR2-ligand binding and to observe the different conformational changes that occur in the protein after the ligand binding. Additionally, we studied the conformational dynamics of N- and C-terminal regions of SSTR2 in the presence and absence of the lipid bilayer. Both the systems were compared to understand the influence of lipid molecules in the formation of secondary structural domains by these extracellular regions. The comparative study revealed that the secondary structural elements formed by C-terminal residues in presence of lipid molecules is crucial for the functioning of SSTR2. Our study results highlight the structural complexities involved in the functioning of SSTR upon binding with the ligands in the presence and absence of lipid bilayer, which is essential for designing novel drug targets.
The Role of Visibility in Silent Speech Tongue Movements: A Kinematic Study of Consonants
Authors: Glotfelty Annette , Katz William F. 
Published: April 2021

Purpose
To better understand the role of tongue visibility in speech, this study compared the spatiotemporal patterns of silent versus audible speech for lingual consonants of American English. Kinematic data were obtained for articulatory features assumed to be visually salient, including tongue movement (anterior displacement and midsagittal area), lip aperture, and consonant duration.

Method
Electromagnetic articulography was used to measure 11 native speakers' productions of five consonants (/ɡ/, /w/, /ɹ/, /l/, and /ð/), selected to represent a continuum of tongue visibility. Nonword consonant–vowel syllables were elicited during a procedure designed to convey a dyadic communication environment. A method of kinematic-based consonant segmentation was developed for data processing, and results were analyzed with repeated-measures analysis of variance.

Results
Findings indicated increased consonant duration and lip aperture in the silent condition (vs. audible) for all five consonants. Tongue forward displacement was slightly greater in the silent condition, compared to audible, for all consonants except /ɡ/, the only consonant without a visible tongue component. In addition, the extent of tongue forwarding in silent speech corresponded with the degree of tongue visibility.

Conclusion
During silent speech, talkers increased their lip aperture and consonant duration and tended to shift their tongues forward for the most visible lingual consonants, suggesting that talkers may be aware at some level of the need to increase articulatory visibility of the tongue in the presence of an interlocutor during adverse speech conditions.
A New Memory Perspective on the Sentence Comprehension Deficits of School-Age Children With Developmental Language Disorder: Implications for Theory, Assessment, and Intervention
Authors: Montgomery James W. , Gillam Ronald B. , Evans Julia L. 
Published: April 2021

Purpose
The nature of the relationship between memory and sentence comprehension in school-age children with developmental language disorder (DLD) has been unclear. We present a novel perspective that highlights the relational influences of fluid intelligence, controlled attention, working memory (WM), and long-term memory (LTM) on sentence comprehension in children with and without DLD. This perspective has new and important implications for theory, assessment, and intervention.

Method
We review a large-scale study of children with and without DLD that focused on the connections between cognition, memory, and sentence comprehension. We also summarize a new model of these relationships.

Results
Our new model suggests that WM serves as a conduit through which syntactic knowledge in LTM, controlled attention, and general pattern recognition indirectly influence sentence comprehension in both children with DLD and typically developing children. For typically developing children, language-based LTM and fluid intelligence indirectly influence sentence comprehension. However, for children with DLD, controlled attention plays a larger indirect role.

Conclusions
WM plays a key role in children's ability to apply their syntactic knowledge when comprehending canonical and noncanonical sentences. Our new model has important implications for the assessment of sentence comprehension and for the treatment of larger sentence comprehension deficits.
A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE)
Authors: Junais  , Boissier S. , Boselli A. , Boquien M. , Longobardi A. , Roehlly Y. , Amram P. , Fossati M. , Cuillandre J.-C. , Gwyn S. , Ferrarese L. , Côté P. , Roediger J. , Lim S. , Peng E. W. , Hensler G. , Trinchieri G. , Koda J. , Prantzos N. 
Published: April 2021

Context. The evolution of galaxies depends on their interaction with the surrounding environment. Ultra-diffuse galaxies (UDGs) have been found in large numbers in clusters. We detected a few star-forming blobs in the VESTIGE survey, located at ∼5 kpc from a UDG, namely NGVS 3543, in association with an HI gas cloud AGC 226178, suggesting a recent interaction between this low-surface-brightness system and the surrounding cluster environment.
Aims. We use a complete set of multi-frequency data including deep optical, UV, and narrow-band Hα imaging and HI data to understand the formation process that gave birth to this peculiar system.
Methods. For this purpose, we measured (i) the multi-wavelength radial surface brightness profiles of NGVS 3543 and compared them to the predictions of spectro-photometric models of galaxy evolution in rich clusters; and (ii) the aperture photometry of the blue regions in the vicinity of NGVS 3543 in order to determine their age and stellar mass.
Results. Comparisons of the observations with evolutionary models indicate that NGVS 3543 has undergone a ram-pressure stripping that peaked ∼100 Myr ago, transforming a blue gas-rich UDG into a red gas-poor UDG. Star formation has taken place in the ram pressure stripped gas, the mass of which is ∼108 M⊙, forming star complexes with a typical age of ∼20 Myr and a stellar mass of ∼104 M⊙.
Conclusions. These results suggest that we are observing for the first time the ongoing transformation of a gas-rich UDG into a red and quiescent UDG under the effect of a ram-pressure stripping event. The same process could explain the lack of star-forming UDGs in rich environments observed in several nearby clusters.
Multiscale behaviour of stellar activity and rotation of the planet host Kepler-30
Authors: de Freitas D. B. , Lanza A. F. , da Silva Gomes F. O. , Das Chagas M. L. 
Published: April 2021

Context. The Kepler-30 system consists of a G dwarf star with a rotation period of ~16 days and three planets orbiting almost coplanar with periods ranging from 29 to 143 days. Kepler-30 is a unique target with which to study stellar activity and rotation in a young solar-like star accompanied by a compact planetary system.
Aims. We use about 4 yr of high-precision photometry collected by the Kepler mission to investigate the fluctuations caused by photospheric convection, stellar rotation, and starspot evolution as a function of timescale. Our main goal is to apply methods for the analysis of time-series to find the timescales of the phenomena that affect the light variations. We correlate those timescales with periodicities in the star and the planetary system.
Methods. We model the flux rotational modulation induced by active regions using spot modelling and apply the Multifractal Detrending Moving Average algorithm in standard and multiscale versions to analyse the behaviour of variability and light fluctuations that can be associated with stellar convection and the evolution of magnetic fields on timescales ranging from less than 1 day up to about 35 days. The light fluctuations produced by stellar activity can be described by the multifractal Hurst index that provides a measure of their persistence.
Results. The spot modelling indicates a lower limit to the relative surface differential rotation of ΔΩ∕Ω ~ 0.02 ± 0.01 and suggests a short-term cyclic variation in the starspot area with a period of ~34 days, which is close to the synodic period of 35.2 days of the planet Kepler-30b. By subtracting the two time-series of the simple aperture photometry and pre-search data conditioning Kepler pipelines, we reduce the rotational modulation and find a 23.1-day period close to the synodic period of Kepler-30c. This period also appears in the multifractal analysis as a crossover of the fluctuation functions associated with the characteristic evolutionary timescales of the active regions in Kepler-30 as confirmed by spot modelling. These procedures and methods may be greatly useful for analysing current TESS and future PLATO data.
Magnetic field inference in active region coronal loops using coronal rain clumps
Authors: Kriginsky M. , Oliver R. , Antolin P. , Kuridze D. , Freij N. 
Published: April 2021

Aims. We aim to infer information about the magnetic field in the low solar corona from coronal rain clumps using high-resolution spectropolarimetric observations in the Ca II 8542 Å line obtained with the Swedish 1 m Solar Telescope.
Methods. The weak-field approximation (WFA) provides a simple tool to obtain the line-of-sight component of the magnetic field from spectropolarimetric observations. We adapted a method developed in a previous paper in order to assess the different conditions that must be satisfied in order to properly use the WFA for the data at hand. We also made use of velocity measurements in order to estimate the plane-of-the-sky magnetic field component, so that the magnetic field vector could be inferred.
Results. We have inferred the magnetic field vector from a data set totalling 100 spectral scans in the Ca II 8542 Å line, containing an off-limb view of the lower portion of catastrophically cooled coronal loops in an active region. Our results, albeit limited by the cadence and signal-to-noise ratio of the data, suggest that magnetic field strengths of hundreds of Gauss, even reaching up to 1000 G, are omnipresent at coronal heights below 9 Mm from the visible limb. Our results are also compatible with the presence of larger magnetic field values such as those reported by previous works. However, for large magnetic fields, the Doppler width from coronal rain is not that much larger than the Zeeman width, thwarting the application of the WFA. Furthermore, we have determined the temperature, T, and microturbulent velocity, ξ, of coronal rain clumps and off-limb spicules present in the same data set, and we have found that the former ones have narrower T and ξ distributions, their average temperature is similar, and coronal rain has microturbulent velocities smaller than those of spicules.
Wind suppression by X-rays in Cygnus X-3
Authors: Vilhu O. , Kallman T. R. , Koljonen K. I. I. , Hannikainen D. C. 
Published: April 2021

Context. The radiatively driven wind of the primary star in wind-fed X-ray binaries can be suppressed by the X-ray irradiation of the compact secondary star. This causes feedback between the wind and the X-ray luminosity of the compact star.
Aims. We aim to estimate how the wind velocity on the face-on side of the donor star depends on the spectral state of the high-mass X-ray binary Cygnus X-3.
Methods. We modeled the supersonic part of the wind by computing the line force (force multiplier) with the Castor, Abbott & Klein formalism and XSTAR physics and by solving the mass conservation and momentum balance equations. We computed the line force locally in the wind considering the radiation fields from both the donor and the compact star in each spectral state. We solved the wind equations at different orbital angles from the line joining the stars and took the effect of wind clumping into account. Wind-induced accretion luminosities were estimated using the Bondi-Hoyle-Lyttleton formalism and computed wind velocities at the compact star. We compared them to those obtained from observations.
Results. We found that the ionization potentials of the ions contributing the most to the line force fall in the extreme-UV region (100–230 Å). If the flux in this region is high, the line force is weak, and consequently, the wind velocity is low. We found a correlation between the luminosities estimated from the observations for each spectral state of Cyg X-3 and the computed accretion luminosities assuming moderate wind clumping and a low mass of the compact star. For high wind clumping, this correlation disappears. We compared the XSTAR method used here with the comoving frame method and found that they agree reasonably well with each other.
Conclusions. We show that soft X-rays in the extreme-UV region from the compact star penetrate the wind from the donor star and diminish the line force and consequently the wind velocity on the face-on side. This increases the computed accretion luminosities qualitatively in a similar manner as observed in the spectral evolution of Cyg X-3 for a moderate clumping volume filling factor and a compact star mass of a few (2–3) solar masses.
Geomagnetically induced currents during the 07–08 September 2017 disturbed period: a global perspective
Authors: Clilverd Mark A. , Rodger Craig J. , Freeman Mervyn P. , Brundell James B. , Mac Manus Daniel H. , Dalzell Michael , Clarke Ellen , Thomson Alan W. P. , Richardson Gemma S. , MacLeod Finlay , Frame Ian 
Published: April 2021

Measurements from six longitudinally separated magnetic observatories, all located close to the 53° mid-latitude contour, are analysed. We focus on the large geomagnetic disturbance that occurred during 7 and 8 September 2017. Combined with available geomagnetically induced current (GIC) data from two substations, each located near to a magnetic observatory, we investigate the magnetospheric drivers of the largest events. We analyse solar wind parameters combined with auroral electrojet indices to investigate the driving mechanisms. Six magnetic field disturbance events were observed at mid-latitudes with dH/dt > 60 nT/min. Co-located GIC measurements identified transformer currents >15 A during three of the events. The initial event was caused by a solar wind pressure pulse causing largest effects on the dayside, consistent with the rapid compression of the dayside geomagnetic field. Four of the events were caused by substorms. Variations in the Magnetic Local Time of the maximum effect of each substorm-driven event were apparent, with magnetic midnight, morning-side, and dusk-side events all occurring. The six events occurred over a period of almost 24 h, during which the solar wind remained elevated at >700 km s−1, indicating an extended time scale for potential GIC problems in electrical power networks following a sudden storm commencement. This work demonstrates the challenge of understanding the causes of ground-level magnetic field changes (and hence GIC magnitudes) for the global power industry. It also demonstrates the importance of magnetic local time and differing inner magnetospheric processes when considering the global hazard posed by GIC to power grids.
Determination of Schottky barrier height of graphene electrode on AlGaN/GaN heterostructure
Authors: Pandit Bhishma , Kim Jaeho , Cho Jaehee 
Published: April 2021

A graphene Schottky contact was fabricated on an AlGaN/GaN heterostructure and subsequently analyzed. The calculated and experimentally measured Schottky barrier heights (SBHs) determined using the theoretical Schottky–Mott model, the thermionic emission model, the temperature-dependent current–voltage measurement, and the capacitance–voltage measurement were observed to be inconsistent, which was attributed to the ambiguities in both the Schottky contact area and the Richardson constant. While excluding the effects of these two factors, an SBH of 0.15 eV was determined by the temperature-dependent Richardson plot. This result was confirmed by calculating the inverse of the square of the measured capacitance with consideration of the threshold voltage required to deplete the two-dimensional electron gas under the Schottky contact.
Epigenetic reprogramming of tumor cell–intrinsic STING function sculpts antigenicity and T cell recognition of melanoma
Authors: Falahat Rana , Berglund Anders , Putney Ryan M. , Perez-Villarroel Patricio , Aoyama Shota , Pilon-Thomas Shari , Barber Glen N. , Mulé James J. 
Published: April 2021

SignificanceAlthough cancer immunotherapies have shown potential in inducing durable tumor regression in patients with metastatic melanoma, their efficacy remains highly variable and patient specific. Here, we present one strategy to overcome resistance to T cell–based immunotherapies by pharmacologically modulating the STING pathway, a relatively common suppressed DNA-sensing pathway in human melanomas. We show that rescue of this pathway in human melanoma cells using a clinically available DNA methylation inhibitor can augment their antigenicity and recognition by tumor-infiltrating lymphocytes. These findings have important clinical implications for the development of optimal therapeutic protocols that consider the status of tumor-intrinsic STING activity and provide a strategy to design clinical interventions using T cell–based immunotherapies with appropriate patient selection in melanoma.
Learning loss due to school closures during the COVID-19 pandemic
Authors: Engzell Per , Frey Arun , Verhagen Mark D. 
Published: April 2021

Significance
School closures have been a common tool in the battle against COVID-19. Yet, their costs and benefits remain insufficiently known. We use a natural experiment that occurred as national examinations in The Netherlands took place before and after lockdown to evaluate the impact of school closures on students’ learning. The Netherlands is interesting as a “best-case” scenario, with a short lockdown, equitable school funding, and world-leading rates of broadband access. Despite favorable conditions, we find that students made little or no progress while learning from home. Learning loss was most pronounced among students from disadvantaged homes.
One-step synthesis of fluorescence-enhanced carbon dots for Fe (III) on−off−on sensing, bioimaging and light-emitting devices
Authors: An Jia , Liu Guoyi , Chen Meizhu , Hu Yongqin , Chen Rubing , Lyu Ying , Zhang Chao , Liu Yufei 
Published: April 2021

Abstract
Carbon quantum dots (CDs), as one of the most potential fluorescent sensing materials, have attracted lots of attention in recent years. However, the low quantum yields, complicated separation and purification procedures have limited its application and large-scale production. In this paper, a facile and universal method was successfully developed to synthesize CDs-silica (SiO2) spheres composites (CS composites), which not only demonstrates 10-fold fluorescence enhancement compared with single CDs but also enables the purification with a simple centrifugation step. Meanwhile, fabricated composites also presented superior photoluminescence (PL) stability and high PL intensity, even in some tough environments such as acid/alkali aqueous solution, high/low temperature, and high ion concentration aqueous solution. This simple, fast, low-cost, and efficient synthesis method would potentially expand the application of CDs for clinical analysis, optical sensing (ferric ion (Fe3+) and pyrophosphate), bioimaging and light-emitting diodes (LEDs).
Structural, dielectric, magnetic and optical properties of double perovskite oxide Sm2NiMnO6 nanoparticles synthesized by a sol−gel process
Authors: Leng Kai , Xia Weiren , Tang Qingkai , Yang Li , Xie Yuting , Wu Zhiwei , Yi Kang , Zhu Xinhua 
Published: April 2021

Abstract
Here we report on the structural, dielectric, magnetic and optical properties of double perovskite Sm2NiMnO6 (SNMO) nanoparticles synthesized by a sol−gel method. Structural Reitveld refinements on x-ray powder diffraction data revealed that the SNMO nanoparticles crystallized in a monoclinic crystal structure with P21/n space group. SEM and (HR)TEM images revealed the phase purity and single-crystalline nature of the SNMO nanoparticles. XPS spectra confirmed the presence of Sm3+, Ni2+ and Mn4+ ions in the SNMO nanoparticles and oxygen in the forms of lattice oxygen and the hydroxyls species. SNMO ceramics exhibited relaxor-type dielectric behavior, well fitted by modified Curie−Weiss law. Such dielectric behavior originated from the interactions of random dipoles arisen from the B-site cations disorder accompanied with the variations in local electric fields and local strain fields due to the different radii of B-site cations, and/or the virtual electrons hopping between the Ni2+ and Mn4+ cations. Magnetic data demonstrate the variations of the magnetic transitions at low temperatures and the spin glass-like behavior below 11 K, which is attributed to the spin fluctuations induced by the competing interactions between the ferromagnetic (FM) and antiferromagnetic phases. Large positive Curie−Weiss temperature (θ
p) indicates the dominant FM super-exchange interactions in the SNMO samples. The SNMO nanoparticles have a direct optical band gap of 1.42 eV, close to 1.34 eV in a single junction solar cell. That enables the SNMO nanoparticles to be useful for solar cell absorbers.