bluuebunny/crossref_metadata_2025_split huggingface dataset:
Search for pairs and groups in the 2006 Geminid meteor shower
Authors: Koten P. , Čapek D. , Spurný P. , Štork R. , Vojáček V. , Bednář J. 
Published: October 2021

Context. The existence of pairs and groups of meteors during meteor showers has been an open question for a long time. The double-station video observation of the 2006 Geminid meteor shower, one of the most active annual showers, is used for the search of such events.
Aims. The goal of the paper is to determine whether the observed pairs of Geminid meteors are real events or cases of random coincidence.
Methods. The atmospheric trajectories of the observed meteors, photometric masses, and both time and spatial distances of meteoroids in the atmosphere were determined using a double-station video observation. The time gaps between them were analysed statistically. The Monte Carlo simulation was used for the determination of the probability of random pairings.
Results. A higher than expected number of candidates for pairs was found among 2006 Geminids. An evaluation of the Poisson distribution shows that a significant fraction of them may be real cases. However, the Monte Carlo simulation did not confirm this result and provided a different view. Analysis of geometrical positions of candidate pairs also did not support the presence of real pairs and groups. Although we cannot exclude that some of them may be physically connected pairs, all the observed cases can be explained as the coincidental appearance of unrelated meteors.
OCCASO
Authors: Carrera R. , Casamiquela L. , Carbajo-Hijarrubia J. , Balaguer-Núñez L. , Jordi C. , Romero-Gómez M. , Blanco-Cuaresma S. , Cantat-Gaudin T. , Lillo-Box J. , Masana E. , Pancino E. 
Published: October 2021

Context.Open clusters (OCs) are widely used as test particles to investigate a variety of astrophysical phenomena, from stellar evolution to Galactic evolution.Gaiaand the complementary massive spectroscopic surveys are providing an unprecedented wealth of information about these systems.Aims.The Open Cluster Chemical Abundances from Spanish Observatories (OCCASO) survey aims to complement all this work by determining OCs’ accurate radial velocities and chemical abundances from high-resolution,R ≥ 60 000, spectra.Methods.Radial velocities were obtained by cross-correlating the observed spectra with a library of synthetic spectra that covers early M to A spectral types.Results.We provide radial velocities for 336 stars including severalGaiabenchmark stars and objects belonging to 51 open clusters. The internal uncertainties of the derived radial velocities go from 10 m s−1to 21 m s−1as a function of the instrumental configuration used. The derived radial velocities, together with theGaiaproper motions, were used to investigate the cluster membership of the observed stars. After this careful membership analysis, we obtained average velocities for 47 open clusters. To our knowledge, this is the first radial velocity determination for five of these clusters. Finally, the radial velocities, proper motions, distances and ages were used to investigate the kinematics of the observed clusters and in the integration of their orbits.
Characterising coronal turbulence using snapshot imaging of radio bursts in 80–200 MHz
Authors: Mohan A. 
Published: October 2021

Context. Metrewave solar type-III radio bursts offer a unique means to study the properties of turbulence across coronal heights. Theoretical models have shown that the apparent intensity and size of the burst sources evolve at sub-second scales under the influence of local turbulence. The properties of the evolution vary with observation frequency. However, observational studies remained difficult due to the lack of high fidelity imaging capabilities at these fine temporal scales simultaneously across wide spectral bands.
Aims. I present a spectroscopic snapshot imaging (0.5 s, 160 kHz resolution) study of a type-III burst event across the 80–200 MHz band. By modelling the temporal variability of the source sizes and intensity at every observation frequency, the characteristics of coronal turbulence are studied across a heliocentric height range of ≈1.54–1.75 R⊙.
Methods. To understand the morphological evolution of the type-III source, a 2D Gaussian fitting procedure is used. The observed trends in the source area and integrated flux density are analysed in the framework of theoretical and data-driven models.
Results. The strength of density fluctuations (δN/N) in the corona is derived as a function of height (R). Combined with the archival low frequency data, δN/N values across ≈1.5–2.2 R⊙ agree within a few factors. The burst decay time (τdecay) and the full width at half maximum of the source showed a power-law dependence with frequency, roughly consistent with the results from data-driven models. However, the values of τdecay across frequencies turned out higher than the expected trend. The intrinsic sizes of the burst source were derived, correcting for scatter broadening. This roughly matched the expected size of flux tubes at the coronal heights explored. I also report the observation of an intrinsic anti-phased pulsation in the area and flux density of the source.
Adopting the Hirschman–Herfindahl Index to estimate the financial sustainability of Vietnamese public universities
Authors: Le Trung Thanh , Nguyen Thuy Linh , Trinh Minh Thong , Nguyen Mai Huong , Nguyen Minh Phuong Thi , Pham Hiep-Hung 
Published: October 2021

AbstractOver several decades, the Vietnamese government has increasingly cut its investment in the public higher education system and has also introduced a cost-sharing mechanism. Under this scheme, Vietnamese public universities have been seeking other sources of revenue. Despite the bold emphasis on the need for revenue diversification in higher education in Vietnam, there is little empirical evidence of the status quo of Vietnamese public higher education finance. The purpose of this paper was to fill this research gap by using the Hirschman–Herfindahl Index to estimate the degree of financial diversity in 51 public universities in Vietnam between 2015 and 2017. Our findings revealed that all institutions in this study were unsustainable due to their weak financial diversity. Suggestions for policy makers and university leaders that may enhance financial sustainability include the adoption of performance-based financial allocations and the implementation of capacity-building programs for universities with regard to fund-raising and entrepreneurship skills.
Force uniformity control for large-area roll-to-roll process
Authors: Nguyen Truong Sinh , Lee Seung-Hyun , Kim Ga Eul , Kwon Sin , Kim Kyung-Rok , Park Pyoungwon , Kim Kwang-Young , Kim Seho , Choi Young-Man , Kim Kyunghoon 
Published: October 2021

Demand for high throughput manufacturing has recently increased in various fields, such as electronics, photonics, optical devices, and energy. Moreover, flexible electronic devices are indispensable in applications such as touch screens, transparent conductive electrodes, transparent film heaters, organic photovoltaics, organic light-emitting diodes, and battery. For these applications, a large-area roll-to-roll (R2R) process is a promising method for producing with high throughput. However, bending deformation of rollers is unavoidable in a large-scale R2R system, which produces non-uniformity in force distribution during processing and reduces the sample quality. In this study, we propose a new R2R imprinting module to mitigate the deformation by using an additional backup roller to achieve uniform force distribution. From numerical simulations, we found that there exists an optimal imprinting force for each backup roller length to obtain the best uniformity. Experimental results using a large-area pressure sensor verified the effectiveness of the proposed method. Finally, the R2R nanoimprint lithography process showed that the proposed method produces patterns of 100 nm width with uniform residual layer thickness, which are distributed across the substrate of 1.2 m width.
A ship-lock-type reactor for ion–molecule reactions of mass-selected ions under high-pressure conditions
Authors: Wei Gong-Ping , Liu Qing-Yu , Ren Yi , He Sheng-Gui 
Published: October 2021

A ship-lock-type reactor has been developed to study ion–molecule reactions of mass-selected ions under high-pressure conditions. Neutral gas molecules can be confined in the reactor by controlling two electromagnet valves to close both the inlet and the outlet of the reactor. Gas-phase ions can be trapped in an ion funnel trap installed in the reactor and interacted with a high-pressure (up to 1000 Pa) reactant gas for a period of time (up to 1 s). The reactions of mass-selected V2O6− with CH4 and n-C4H10 and mass-selected Au+ with n-C7H16 were investigated to evaluate the performance of the reactor. The hydrogen atom abstraction product V2O6H− was observed for the reaction of V2O6− with CH4, the rate constant was measured to be (1.9 ± 0.4) × 10−16 cm3 molecule−1 s−1, and the kinetic isotope effect value was determined to be 5.4 ± 1.1. Furthermore, the detection limit of n-C7H16 with 1-min measurements was determined to be (19 ± 2) pptv, which is significantly lower than those in previous studies. These results indicate that the current apparatus is a prospective for the study of slow ion–molecule reactions and the detection of trace amounts of gas species, such as volatile organic compounds.
Cr2O3 layer inhibits agglomeration of phosphine-protected Au9 clusters on TiO2 films
Authors: Alotabi Abdulrahman S. , Yin Yanting , Redaa Ahmad , Tesana Siriluck , Metha Gregory F. , Andersson Gunther G. 
Published: October 2021

The properties of semiconductor surfaces can be modified by the deposition of metal clusters consisting of a few atoms. The properties of metal clusters and of cluster-modified surfaces depend on the number of atoms forming the clusters. Deposition of clusters with a monodisperse size distribution thus allows tailoring of the surface properties for technical applications. However, it is a challenge to retain the size of the clusters after their deposition due to the tendency of the clusters to agglomerate. The agglomeration can be inhibited by covering the metal cluster modified surface with a thin metal oxide overlayer. In the present work, phosphine-protected Au clusters, Au9(PPh3)8(NO3)3, were deposited onto RF-sputter deposited TiO2 films and subsequently covered with a Cr2O3 film only a few monolayers thick. The samples were then heated to 200 °C to remove the phosphine ligands, which is a lower temperature than that required to remove thiolate ligands from Au clusters. It was found that the Cr2O3 covering layer inhibited cluster agglomeration at an Au cluster coverage of 0.6% of a monolayer. When no protecting Cr2O3 layer was present, the clusters were found to agglomerate to a large degree on the TiO2 surface.
Thermal convection in a tilted rectangular box
Authors: Xia Shu-Ning , Wu Jian-Zhao , Wan Zhen-Hua , Wang Bo-Fu , Lu Zhi-Ming , Zhou Quan 
Published: October 2021

Thermal convection in a tilted three-dimensional rectangular box has been systematically investigated by direct numerical simulation. The Rayleigh number Ra varies from 107 to 109, the Prandtl number Pr is set to 0.7, and the tilted angle β ranges from 0° to 90°. The effects of tilting on large-scale circulation (LSC), Nusselt number (Nu), Reynolds number (Re), and boundary layers (BLs) and the Ra-dependency are investigated. For large β exceeding certain values, say 45°, the stable temperature stratification forms in the bulk, resulting in low Re and Nu. It is found that the tilting leads to a distinct trend for Nu and Re: Nu first increases to some extent for small β, then nearly stays unchanged for moderate β, and finally decreases for large β, while Re initially increases for small β and then directly declines with increasing β. Based on the analysis of flow structures, with increasing β, it is found that the volume of the high-velocity tube (HVT) initially increases for 107 ≤ Ra ≤ 108 but decreases for Ra = 109, which is responsible for the variation in Nu at small β. The probability density functions of instantaneous convective heat transport within the HVT show higher probabilities for large values when β increases, implying that LSC tends to be more coherent and causing different tilting behaviors between Nu and Re. Finally, we find that, except for β = 90°, the normalized profiles of viscous and thermal BLs tend to have universal profiles, deviating from the BL of the Prandtl–Blasius–Pohlhausen (PBP) type to some extent regardless of β. Only the thermal BL for β = 90° is found to be in good agreement with the classic PBP laminar BL profile.
Conservation agriculture improves soil physical properties and crop productivity: a long-term study in middle Indo-Gangetic Plains of India
Authors: Rao K. K. , Samal S. K. , Poonia S. P. , Kumar Rakesh , Mishra J. S. , Bhatt B. P. , Dwivedi S. K. , Mondal S. , Choubey A. K. , Kumar Santosh , Kumar Manoj , Malik R. K. , Dalal R. C. 
Published: October 2021

Context Conservation agriculture (CA) can potentially arrest deteorating soil fertility and improve crop production in the middle Indo-Gangetic Plains of India. Methods A field experiment (ICAR RCER, Patna, India; 2009–2016) tested four common farming practices: S1, a wheat–rice fallow rotation with complete removal of crop residues; S2, best management practices (BMPs) with puddled transplanted rice, drill-seeded wheat in no-tillage (NT), and drill-seeded mungbean in conventional tillage (CT) in a wheat–mungbean–rice rotation where residues were retained on surface in rice and wheat, and residue incorporated in mungbean; S3, CA system in a wheat–cowpea–rice rotation; and S4, BMP intensified and diversified cropping system in a potato + maize–cowpea–rice rotation (unpuddled transplanted rice with dribbled maize + potato, intercropped) in CT and relayed dibbling of cowpea in NT. Full residues of potato and cowpea were incorporated and one-third portion of rice and maize residue were retained on soil. Key results After 7 years, S2, S3 and S4 systems lowered soil bulk density and penetration resistance compared to S1. S3 resulted in higher soil macro-aggregates (>0.125 mm) and lower soil micro-aggregates (<0.125 mm). Avoiding tillage in wheat and including a food legume in rotation in S2 increased annual rice equivalent yields by 30.5–34.4%. S4 had the highest water productivity (1.04 kg rice equivalent grain m−3) and S1 had the lowest (0.64 kg rice equivalent grain m−3). Conclusions and implications NT and retention of crop residues have potential to improve soil health and monetary gains.
An uncommon neuronal class conveys visual signals from rods and cones to retinal ganglion cells
Authors: Young Brent K. , Ramakrishnan Charu , Ganjawala Tushar , Wang Ping , Deisseroth Karl , Tian Ning 
Published: October 2021

SignificanceCell classes are the building blocks for the central nervous system. It is widely believed that major neuronal classes have been identified in the retina, although some types in the amacrine cell class have not been fully characterized. Here, we describe a retinal interneuron that does not fit into any existing retinal cell class, and we name them Campana cells. Although Campana cells relay visual signals from photoreceptors to the retinal ganglion cells, they differ from bipolar cells in many morphological, physiological, and molecular features. They are also significantly different from amacrine cells. Therefore, our results open the possibility for an unconventional retinal cell class that plays unique roles in visual processing.
An ultra-low-cost electroporator with microneedle electrodes (ePatch) for SARS-CoV-2 vaccination
Authors: Xia Dengning , Jin Rui , Byagathvalli Gaurav , Yu Huan , Ye Ling , Lu Chao-Yi , Bhamla M. Saad , Yang Chinglai , Prausnitz Mark R. 
Published: October 2021

Significance
Low-cost and rapidly distributable vaccines are urgently needed to combat COVID-19 and future pandemics, especially for developing countries and other low-resource settings. DNA vaccines are inexpensive, rapidly developed, and safe, but require bulky and expensive electroporation devices for effective vaccination, which presents challenges to affordable and mass vaccination. We developed an ultra-low-cost (<1 USD), handheld (<50 g), battery-free electroporation system combining a thumb-actuated piezoelectric pulser and a microneedle electrode array skin interface for DNA vaccination against COVID-19, which was shown to be immunogenic and well-tolerated in animal studies. This study provides a proof-of-concept that DNA vaccination against epidemics can be achieved using an ultra-low-cost electroporator that is inexpensive enough for single use and robust enough for repeated use if desired.
Monoclonal antibody-mediated neutralization of SARS-CoV-2 in an IRF9-deficient child
Authors: Lévy Romain , Zhang Peng , Bastard Paul , Dorgham Karim , Melki Isabelle , Hadchouel Alice , Hartoularos George C. , Neven Bénédicte , Castelle Martin , Roy Charlotte , Toin Tom , Berteloot Laureline , Bizien Lucy , Abid Hanène , Burgard Marianne , Houhou-Fidouh Nadhira , Rozenberg Flore , Jouanguy Emmanuelle , Ye Chun Jimmie , Gorochov Guy , Zhang Qian , Casanova Jean-Laurent 
Published: October 2021

Significance
Life-threatening COVID-19 pneumonia can be caused by rare inborn errors of type I interferon (IFN) immunity, or by autoantibodies neutralizing IFN-α2 or IFN-ω. In 2018, we reported a girl with critical influenza pneumonia due to inherited IRF9 deficiency, a component of the ISGF-3 transcription factor. We report the course of COVID-19 in the same patient. She was admitted on day 1 of upper respiratory tract infection with viremia. Administration of SARS-CoV-2–specific neutralizing monoclonal antibodies on day 2 prevented the development of pneumonia. SARS-CoV-2–specific monoclonal antibodies were sufficient to overcome a lack of ISGF-3– and IRF9-dependent type I and type III IFN immunity to the virus. They should be considered in selected children at high risk of life-threatening COVID-19.
Quantum isotropy and the reduction of dynamics in Bianchi I
Authors: Beetle C , Engle J S , Hogan M E , Mendonça P 
Published: October 2021

Abstract
The authors previously introduced a diffeomorphism-invariant definition of a homogeneous and isotropic sector of loop quantum gravity (LQG), along with a program to embed loop quantum cosmology (LQC) into it. The present paper works out that program in detail for the simpler, but still physically non-trivial, case where the target of the embedding is the homogeneous, but not isotropic, Bianchi I model. The diffeomorphism-invariant conditions imposing homogeneity and isotropy in the full theory reduce to conditions imposing isotropy on an already homogeneous Bianchi I spacetime. The reduced conditions are invariant under the residual diffeomorphisms still allowed after gauge fixing the Bianchi I model. We show that there is a unique embedding of the quantum isotropic model into the homogeneous quantum Bianchi I model that (a) is covariant with respect to the actions of such residual diffeomorphisms, and (b) intertwines both the (signed) volume operator and at least one directional Hubble rate. That embedding also intertwines all other operators of interest in the respective loop quantum cosmological models, including their Hamiltonian constraints. It thus establishes a precise equivalence between dynamics in the isotropic sector of the Bianchi I model and the quantized isotropic model, and not just their kinematics. We also discuss the adjoint relationship between the embedding map defined here and a projection map previously defined by Ashtekar and Wilson-Ewing. Finally, we highlight certain features that simplify this reduced embedding problem, but which may not have direct analogues in the embedding of homogeneous and isotropic LQC into full LQG.
Emergent gravity and D-brane adiabatic dynamics: emergent Lorentz connection
Authors: Viennot David 
Published: October 2021

Abstract
We explore emergent geometry of the spacetime at the microscopic scale by adiabatic transport of a quasi-coherent state of a fermionic string, with quantum spacetime described by the matrix theory (BFSS matrix model). We show that the generator of the Berry phase is the shift vector of the spacetime foliation by spacelike surfaces associated with the quasi-coherent state. The operator-valued generator of the geometric phase of weak adiabatic transport is the Lorentz connection of the emergent geometry which is not torsion free at the microscopic scale. The effects of the torsion seem consistent with the usual interpretation of the Berry curvature as a pseudo magnetic field.
Electron and positron backscattering from condensed targets
Authors: Sinha Nidhi , Subraveti Priyanka , Antony Bobby 
Published: October 2021

Abstract
The backscattering process for electron and positron impinging on condensed targets is studied here. The calculation is performed for Li, Na, Al and Cu atoms in the 500–3000 eV energy range. The well known Vicanek and Urbassek theory is used to determine the backscattering coefficient for present solid atoms. To analyze the elastic scattering cross section, spherical complex optical potential formalism is used. Apart from the backscattering coefficient, momentum transfer cross section, range of penetration, and mean number of wide-angle collisions are also tabulated and compared to the available data. No previous work was found reporting the range of penetration for the atoms. Hence, we also report the electron backscattering coefficient and range of penetration for liquid water for which experimental and theoretical data are available for the range of penetration. The electron backscattering coefficient for liquid water is reported for the first time here.
Ternary SiGeSn alloy nanocrystals via nonthermal plasma synthesis
Authors: Pach Gregory F , Urias-Cordero Fernando , Yazdi Sadegh , Neale Nathan R 
Published: October 2021

Abstract
We report on the synthesis of ternary SiGeSn nanocrystals (NCs) produced via nonthermal plasma synthesis from silane (SiH4), germane (GeH4), and tetramethylstannane (Sn(CH3)4) precursor sources. Detailed structural, chemical, and vibrational analyses show that all three elements are incorporated both on the NC surface and within the NC core. Incorporation of Sn into the NC core is realized using a secondary injection of SiH4 and GeH4 precursor gases in the after-glow region of the plasma, which kinetically traps Sn in the core. We demonstrate compositional tunability of the SiGeSn NCs in which the Si and Ge ratios can be varied broadly at low Sn concentrations. We also show tunability of the Sn content up to ∼2 atomic percent as revealed by ICP-MS analysis. More generally, this report demonstrates how nonthermal plasma synthesis can be used to produce metastable ternary nanostructured alloys involving thermodynamically insoluble constituents.