bluuebunny/crossref_metadata_2025_split huggingface dataset:
Possible hadronic origin of TeV photon emission from SNR G106.3+2.7
Authors: Yang Chuyuan , Zeng Houdun , Bao Biwen , Zhang Li 
Published: December 2021

Context. Recently, HAWC, ASγ, and LHAASO experiments have reported the gamma-ray spectrum of supernova remnant (SNR) G106.3+2.7 above 40 TeV, indicating that SNR G106.3+2.7 is a promising PeVatron candidate. However, the origin of the gamma-ray spectrum is still debated. Thus, a dedicated theoretical model with self-consistent descriptions is required to decipher the properties of the gamma-ray spectrum for this specific source.
Aims. We construct a theoretical model to explain the multiband photon emission from the PeVatron SNR G106.3+2.7.
Methods. In our model, the acceleration and propagation of particles from the Bohm-like diffusion region inside the SNR to the Galactic diffusion region outside the SNR are described through nonlinear diffusive shock acceleration (NLDSA). The main content of our NLDSA model is solving the hydrodynamic equations numerically for gas density, gas velocity, and gas pressure and the equation for the quasi-isotropic particle momentum distribution. The consequent multiband nonthermal emission stems from two different regions, namely the acceleration region and the escaping region.
Results. Our model is capable of explaining the multiband photon emission via the dominant synchrotron radiation of the electrons accelerated inside the SNR. The photons with energy of ≳GeV are naturally produced by the protons inside and outside the SNR. Moreover, photons in the energy range of ~1−~ 100 TeV are due to the interaction of escaped protons with dense molecular clouds.
Conclusions. For photons with energy Eγ ≳ 1 GeV from SNR G106.3+2.7, our results here favor a hadronic origin, where the photons in the energy range of ~1G eV to ~1 TeV are produced inside the SNR through proton-proton interaction, while photons with Eγ ≳ 1 TeV originate from the interaction of escaped protons with a dense molecular cloud.
The extended atmosphere and circumstellar environment of the cool evolved star VX Sagittarii as seen by MATISSE
Authors: Chiavassa A. , Kravchenko K. , Montargès M. , Millour F. , Matter A. , Freytag B. , Wittkowski M. , Hocdé V. , Cruzalèbes P. , Allouche F. , Lopez B. , Lagarde S. , Petrov R. G. , Meilland A. , Robbe-Dubois S. , Hofmann K.-H. , Weigelt G. , Berio P. , Bendjoya P. , Bettonvil F. , Domiciano de Souza A. , Heininger M. , Henning Th. , Isbell J. W. , Jaffe W. , Labadie L. , Lehmitz M. , Meisenheimer K. , Soulain A. , Varga J. , Augereau J.-C. , van Boekel R. , Burtscher L. , Danchi W. C. , Dominik C. , Drevon J. , Gámez Rosas V. , Hogerheijde M. R. , Hron J. , Klarmann L. , Kokoulina E. , Lagadec E. , Leftley J. , Mosoni L. , Nardetto N. , Paladini C. , Pantin E. , Schertl D. , Stee P. , Szabados L. , Waters R. , Wolf S. , Yoffe G. 
Published: December 2021

Context. VX Sgr is a cool, evolved, and luminous red star whose stellar parameters are difficult to determine, which affects its classification.
Aims. We aim to spatially resolve the photospheric extent as well as the circumstellar environment.
Methods. We used interferometric observations obtained with the MATISSE instrument in the L (3–4 μm), M (4.5–5 μm), and N (8–13 μm) bands. We reconstructed monochromatic images using the MIRA software. We used 3D radiation-hydrodynamics simulations carried out with CO5BOLD and a uniform disc model to estimate the apparent diameter and interpret the stellar surface structures. Moreover, we employed the radiative transfer codes OPTIM3D and RADMC3D to compute the spectral energy distribution for the L, M, and N bands, respectively.
Results. MATISSE observations unveil, for the first time, the morphology of VX Sgr across the L, M, and N bands. The reconstructed images show a complex morphology with brighter areas whose characteristics depend on the wavelength probed. We measured the angular diameter as a function of the wavelength and showed that the photospheric extent in the L and M bands depends on the opacity through the atmosphere. In addition to this, we also concluded that the observed photospheric inhomogeneities can be interpreted as convection-related surface structures. The comparison in the N band yielded a qualitative agreement between the N-band spectrum and simple dust radiative transfer simulations. However, it is not possible to firmly conclude on the interpretation of the current data because of the difficulty in constraing the model parameters using the limited accuracy of our absolute flux calibration.
Conclusions. MATISSE observations and the derived reconstructed images unveil the appearance of VX Sgr’s stellar surface and circumstellar environment across a very large spectral domain for the first time.
Increased Risk for Maternal Anxiety during the COVID-19 Outbreak in Brazil among Pregnant Women without Comorbidities
Authors: Nomura Roseli Mieko Yamamoto , Ubinha Ana Carla Franco , Tavares Isabela de Paula , Costa Maria Laura , Opperman Maria Lucia da Rocha , Brock Marianna Facchinetti , Trapani Alberto , Damásio Lia Cruz Vaz da Costa , Reis Nadia Stella Viegas , Borges Vera Therezinha Medeiros , Zaconeta Alberto Carlos Moreno , Araujo Ana Cristina Pinheiro Fernandes de , Ruano Rodrigo 
Published: December 2021

Abstract
Objective To study maternal anxiety in pregnant women without comorbidities in the context of the COVID-19 outbreak in Brazil and to study maternal knowledge and concerns about the pandemic.
Methods This is a secondary analysis from a national multicenter cross-sectional study performed in 10 cities, from June to August, 2020, in Brazil. Interviewed postpartum women, without medical or obstetrical comorbidities, were included in the present subanalysis. A structured questionnaire and the Beck Anxiety Inventory (BAI) were applied.
Results Out of the 1,662 women, 763 (45.9%) met the criteria for the current analysis and 16.1% presented with moderate and 11.5% with severe maternal anxiety. Moderate or severe maternal anxiety was associated with high school education (odds ratio [OR]:1.58; 95% confidence interval [CI]:1.04–2.40). The protective factor was cohabiting with a partner (OR: 0.46; 95%CI: 0.29–0.73). There was a positive correlation between the total BAI score and receiving information about care in the pandemic (rpartial 0.15; p < 0.001); concern about vertical transmission of COVID-19 (rpartial 0.10; p = 0.01); receiving information about breastfeeding (rpartial 0.08; p = 0.03); concerns about prenatal care (rpartial 0.10; p = 0.01), and concerns about the baby contracting COVID-19 (rpartial 0.11; p = 0.004). The correlation was negative in the following aspects: self-confidence in protecting from COVID-19 (rpartial 0.08; p = 0.04), having learned (rpartial 0.09; p = 0.01) and self-confidence in breastfeeding (rpartial 0.22; p < 0.001) in the context of the pandemic.
Conclusion The anxiety of pregnant women without medical or obstetrical comorbidities was associated to high school educational level and not living with a partner during the COVID-19 pandemic. Self-confidence in protecting against COVID-19 and knowledge about breastfeeding care during the pandemic reduced maternal anxiety.
Design of an insertable cone-shaped gradient coil matrix for head imaging with a volumetric finite-difference method
Authors: Kang Liyi , Tang Fangfang , Xia Ling , Liu Feng 
Published: December 2021

Matrix gradient coils have received increasing interest in generating arbitrary-shaped magnetic fields for various magnetic resonance imaging applications. In this paper, a novel cone-shaped matrix gradient coil is proposed to design a multifunctional insertable system for head imaging. Using a volumetric finite-difference-based method, the matrix coil is designed to have comprised several coil elements that can implement localized imaging and control eddy current, dissipated power, and minimum wire gap. With the lowest total dissipated power, various current configurations are selected to generate multiple gradient fields within a large, spheroidal region of interest (ROI) and two small spherical sub-ROIs. The numerical computation results show that the designed matrix coil offers high flexibility in generating a local gradient field capable of improving the local resolution. In addition, with enhanced coil performance, the cone-shaped structure provides a patient-friendly solution for head imaging.
Ag nanoplatelets as efficient photosensitizers for TiO2 nanorods
Authors: Fang Hui , Wilhelm Michael J. , Ma Jianqiang , Rao Yi , Kuhn Danielle L. , Zander Zachary , DeLacy Brendan G. , Dai Hai-Lung 
Published: December 2021

The lifetime for injecting hot electrons generated in Ag nanoplatelets to nearby TiO2 nanorods was measured with ultrafast transient IR absorption to be 13.1 ± 1.5 fs, which is comparable to values previously reported for much smaller spherical Ag nanoparticles. Although it was shown that the injection rate decreases as the particle size increases, this observation can be explained by the facts that (1) the platelet has a much larger surface to bulk ratio and (2) the platelet affords a much larger surface area for direct contact with the semiconductor. These two factors facilitate strong Ag–TiO2 coupling (as indicated by the observed broadened surface plasmon resonance band of Ag) and can explain why Ag nanoplatelets have been found to be more efficient than much smaller Ag nanoparticles as photosensitizers for photocatalytic functions. The fast injection rate, together with a stronger optical absorption in comparison with Au and dye molecules, make Ag nanoplatelets a preferred photosensitizer for wide bandgap semiconductors.
AnchorWave: Sensitive alignment of genomes with high sequence diversity, extensive structural polymorphism, and whole-genome duplication
Authors: Song Baoxing , Marco-Sola Santiago , Moreto Miquel , Johnson Lynn , Buckler Edward S. , Stitzer Michelle C. 
Published: December 2021

Significance
One fundamental analysis needed to interpret genome assemblies is genome alignment. Yet, accurately aligning regulatory and transposon regions outside of genes remains challenging. We introduce Anchored Wavefront alignment (AnchorWave), which implements a genome duplication informed longest path algorithm to identify collinear regions and performs base pair–resolved, end-to-end alignment for collinear blocks using an efficient two-piece affine gap cost strategy. AnchorWave improves the alignment under a number of scenarios: genomes with high similarity, large genomes with high transposable element activity, genomes with many inversions, and alignments between species with deeper evolutionary divergence and different whole-genome duplication histories. Potential use cases include genome comparison for evolutionary analysis of nongenic sequences and population genetics of taxa with large, repeat-rich genomes.
International students’ language socialization in an English-medium university
Authors: Soltani Behnam , Zhang Lawrence Jun 
Published: December 2021

Abstract
This article investigates second language socialization of three international students in a tertiary institute in New Zealand. To understand the experiences of international students, the article draws on the theoretical framework of the production of space to examine how the students experienced their new social space. The article uses multiple sources of data including video/audio recordings of the classroom interaction, field notes, interviews with the focal students/teachers/tutors/lecturers, diaries, and institutional documents to provide a thick description of students’ participation, language socialization, and identities. It does a within and across case analysis of the students’ experience to situate the learning experiences but at the same time to highlight the role of space as a participating social being in the socialization process. The concepts of language socialization and identities are reconceptualized as ever-evolving and ever-changing phenomena, whose production depends on the social conditions and relationships in the social space.
Testing the Principle of No Synonymy across levels of abstraction
Authors: Laporte Samantha , Larsson Tove , Goulart Larissa 
Published: December 2021

AbstractThis corpus-based study tests the Principle of No Synonymy across levels of abstraction by examining the syntactic realizations of subject extraposition (e.g.,it is important to, it seems that), and by investigating at which level(s) of formal description a difference in form also entails a difference in function. The results show that distinct pairs of form and function, i.e. constructions, can be found at different levels of abstraction, but that these constructions also subsume formal realization patterns that do not encode a difference in function. This suggests that the Principle of No Synonymy largely breaks down at low levels of formal description. The study also offers a constructional account of subject extraposition by identifying a number of subject extraposition constructions, thereby showing that this is a syntactic phenomenon that is best analyzed as a family of constructions.
Interaction of excitons with Cherenkov radiation in WSe2 beyond the non-recoil approximation
Authors: Chahshouri Fatemeh , Taleb Masoud , Diekmann Florian K , Rossnagel Kai , Talebi Nahid 
Published: December 2021

Abstract
Cherenkov radiation (CR) from electrons propagating in materials with a high refractive index have applications in particle-detection mechanisms and could be used for high-yield coherent electron beam-driven photon sources. However, the theory of the CR has been treated up to now using the non-recoil approximation, which neglects the effect of electron deceleration in materials. Here, we report on the effect of electron-beam deceleration on the radiated spectrum and exciton-photon interactions in nm-thick WSe2 crystals. The calculation of the CR is performed by simulating the kinetic energy of an electron propagating in a thick sample using the Monto Carlo method combined with the Lienard–Wiechert retarded potential. Using this approach, we numerically investigate the interaction between the excitons and generated photons (CR) beyond the non-recoil approximation and are able to reproduce experimental cathodoluminescence spectra. Our findings pave the way for an accurate design of particle scintillators and detectors, based on the strong-coupling phenomenon.
A novel self-injection relativistic backward wave oscillator
Authors: Fan Zhiqiang , Sun Jun , Cao Yibing , Song Zhimin , Shi Yanchao , Hua Ye , Wu Ping 
Published: December 2021

Abstract
A novel self-injection relativistic backward wave oscillator (RBWO) has been proposed. By introducing a self-injection path into the RBWO, a small portion of the energy in the reflector can be coupled to the upstream of the reflector, and then the formed electric field in the self-injection path region can pre-modulate the passing electron beam, to promote a frequency-locking oscillation of the electron beam. The pre-modulated electron beam can be expected to enhance the beam-wave interaction and suppress parasitic mode oscillation, which is beneficial for maintaining the dominant role of the operating mode. The proposed self-injection RBWO shows great potential for improving the conversion efficiency and pulse duration time. Through particle-in-cell simulation, a microwave with a power of 10.6 GW is obtained, when the beam voltage is 1.08 MeV, and the beam current is 18.6 kA. The conversion efficiency is 53%.
Theoretical analysis and general characteristics for nonlinear vibration energy harvesters
Authors: Wu Hanxiao , Tao Zhi , Li Haiwang , Xu Tiantong , Wang Wenbin , Sun Jiamian 
Published: December 2021

Abstract
In this paper, we present a systematic theoretical and numerical study of the output performance of nonlinear energy harvesters. The general analytical expression of output power for systems with different combinations of nonlinear stiffness and nonlinear damping, as well as symmetrical and asymmetrical systems, have been derived based on harmonic balance method, observing compliance with numerical results. We theoretically prove that there is a limit power for all nonlinear systems which is determined exclusively by the vibrator mass, excitation acceleration, and mechanical damping. The results also indicate that for symmetrical stiffness systems, the asymmetrical damping components have no effect on the output performance. Additionally, we derived semi-analytical solutions of the matching loads and numerically investigated the influence of nonlinear coefficients on the output power with matched load. When the load matches device parameters and is much larger than the internal resistance, the equivalent time-average damping is equal to the mechanical damping. Although the matching load and output power vary with the nonlinear coefficients, the normalized power and matching resistance ratio follow a power function, named matching power line, which is independent of the structural parameters. With the improvement of the equivalent time-average short-circuit damping in the vibration range, the normalized power moves to the right end of the matching power line, and the output power approach to the limit power. These conclusions provide general characteristics of nonlinear energy harvesters, which can be used to guide the design and optimization of energy harvesters.
Modulation of persistent current in graphene quantum rings
Authors: Araújo F R V , da Costa D R , Chaves A J C , de Sousa F E B , Pereira J M 
Published: December 2021

Abstract
We investigate the effect of long-range impurity potentials on the persistent current of graphene quantum rings in the presence of an uniform perpendicular magnetic field. The impurity potentials are modeled as finite regions of the ring with a definite length. We show that, due to the relativistic and massless character of the charge carriers in graphene, the effect of such non-uniform potentials on the energy spectrum and on the persistent current of the rings can be reliably modeled by assuming a non-perturbed ring and including an additional phase due to the interaction of the charge carriers with the potential. In addition, the results show the presence of localized states in the impurity regions. Moreover, we show that for the case of a potential created by a p-n-p junction, the persistent current can be modulated by controlling the voltage at the junction.
Spin Torque Oscillations Triggered by In-plane Field
Authors: Arun R , Gopal R , Chandrasekar V. K. , Lakshmanan M 
Published: December 2021

Abstract
We study the dynamics of a spin torque nano oscillator that consists of parallelly magnetized free and pinned layers by numerically solving the associated Landau-Lifshitz-Gilbert-Slonczewski equation in the presence of a field-like torque. We observe that an in-plane magnetic field which is applied for a short interval of time ($<$1ns) triggers the magnetization to exhibit self-oscillations from low energy initial magnetization state. Also, we confirm that the frequency of oscillations can be tuned over the range $\sim$25 GHz to $\sim$72 GHz by current, even in the absence of field-like torque. We find the frequency enhancement up to 10 GHz by the presence of field-like torque. We determine the Q-factor for different frequencies and show that it increases with frequency. Our analysis with thermal noise confirms that the system is stable against thermal noise and the dynamics is not altered appreciably by it.
Neutron diffraction and ab initio studies on the fully compensated ferrimagnetic characteristics of Mn2V1−x
Co
x
Ga Heusler alloys
Authors: Midhunlal P V , Venkatesh C , Chelvane J Arout , Babu P D , Kumar N Harish 
Published: December 2021

Abstract
Neutron diffraction and ab initio studies were carried out on Mn2V1−x
Co
x
Ga (x = 0, 0.25, 0.5, 0.75, 1) Heusler alloys which exhibits high T
C fully compensated ferrimagnetic characteristics for x = 0.5. A combined analysis of neutron diffraction and ab initio calculations revealed the crystal structure and magnetic configuration which could not be determined from the x-ray diffraction and magnetic measurements. As reported earlier, Rietveld refinement of neutron diffraction data confirmed L21 structure for Mn2VGa and X
a structure for Mn2CoGa. The alloys with x = 0.25 and 0.5 possess L21 structure with Mn(C)–Co disorder. As the Co concentration reaches 0.75, a structural transition has been observed from disordered L21 to disordered X
a. Detailed ab initio studies also confirmed this structural transition. The reason for the magnetic moment compensation in Mn2(V1−x
Co
x
)Ga was identified to be different from that of the earlier reported fully compensated ferrimagnet (MnCo)VGa. With the help of neutron diffraction and ab initio studies, it is identified that the disordered L21 structure with antiparallel coupling between the ferromagnetically aligned magnetic moments of (Mn(A)–Mn(C)) and (V–Co) atom pairs enables the compensation in Mn2V1−x
Co
x
Ga.
Gearbox compound fault diagnosis based on a combined MSGMD–MOMEDA method
Authors: Zhang Jianqun , Zhang Qing , Qin Xianrong , Sun Yuantao , Zhang Jun 
Published: December 2021

Abstract
Weak fault detection is a complex and challenging task when two or more faults (i.e. a compound fault) with discordant severity occur in different parts of a gearbox. The weak fault features are prone to be submerged by the severe fault features and strong background noise, which easily lead to a missed diagnosis. To solve this problem, a novel diagnosis method combining multi-symplectic geometry mode decomposition (MSGMD) and multipoint optimal minimum entropy deconvolution adjusted (MOMEDA) is proposed for gearbox compound fault in this paper. Specifically, different fault components are separated by an improved symplectic geometry mode decomposition (SGMD), namely the MSGMD method. The weak fault features are enhanced by the MOMEDA. In the process of research, a new scheme of selecting the key parameters for MOMEDA is proposed, which is a key step in the practical application of MOMEDA. Compared with SGMD, the proposed MSGMD has two main improvements, including suppressing mode mixing and preventing the generation of pseudo-components. Compared with the original method of selecting parameters based on multipoint kurtosis, the proposed MOMEDA parameter-selecting scheme has the merits of higher accuracy and greater precision. The analysis results of two cases, of simulation and an experiment signal, reveal that the MSGMD–MOMEDA method can accurately diagnose gearbox compound fault even under strong background noise.