bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Galactic center chimneys: the base of the multiphase outflow of the Milky Way
Authors: Ponti G. , Morris M. R. , Churazov E. , Heywood I. , Fender R. P. 
Published: January 2021

Context.Outflows and feedback are key ingredients of galaxy evolution. Evidence for an outflow arising from the Galactic center (GC) – the so-called GC chimneys – has recently been discovered at radio, infrared, and X-ray bands.Aims.We undertake a detailed examination of the spatial relationships between the emission in the different bands in order to place constraints on the nature and history of the chimneys and to better understand their impact on the GC environment and their relation with Galactic scale outflows.Methods.We compare X-ray, radio, and infrared maps of the central few square degrees.Results.The X-ray, radio, and infrared emissions are deeply interconnected, affecting one another and forming coherent features on scales of hundreds of parsecs, therefore indicating a common physical link associated with the GC outflow. We debate the location of the northern chimney and suggest that it might be located on the front side of the GC because of a significant tilt of the chimneys toward us. We report the presence of strong shocks at the interface between the chimneys and the interstellar medium, which are traced by radio and warm dust emission. We observe entrained molecular gas outflowing within the chimneys, revealing the multiphase nature of the outflow. In particular, the molecular outflow produces a long, strong, and structured shock along the northwestern wall of the chimney. Because of the different dynamical times of the various components of the outflow, the chimneys appear to be shaped by directed large-scale winds launched at different epochs. The data support the idea that the chimneys are embedded in an (often dominant) vertical magnetic field, which likely diverges with increasing latitude. We observe that the thermal pressure associated with the hot plasma appears to be smaller than the ram pressure of the molecular outflow and the magnetic pressure. This leaves open the possibility that either the main driver of the outflow is more powerful than the observed hot plasma, or the chimneys represent a “relic” of past and more powerful activity.Conclusions.These multiwavelength observations corroborate the idea that the chimneys represent the channel connecting the quasi-continuous, but intermittent, activity at the GC with the base of theFermibubbles. In particular, the prominent edges and shocks observed in the radio and mid-infrared bands testify to the most powerful, more recent outflows from the central parsecs of the Milky Way.
COVID-19 als Berufskrankheit oder Arbeitsunfall: Überlegungen zu Versicherungsschutz und Meldepflicht in der gesetzlichen Unfallversicherung
Authors: Nowak Dennis , Ochmann Uta , Brandenburg Stephan , Nienhaus Albert , Woltjen Michael 
Published: January 2021

ZusammenfassungEine COVID-19-Erkrankung kann Berufskrankheit oder Arbeitsunfall sein. Eine Anerkennung als Berufskrankheit 3101 kann erfolgen, wenn die Erkrankung bei versicherten Personen auftritt, die infolge der Ausübung ihrer beruflichen Tätigkeit in einem von vier Bereichen einer gegenüber der Allgemeinbevölkerung wesentlich erhöhten Infektionsgefahr ausgesetzt waren: (1) Gesundheitsdienst, (2) Wohlfahrtspflege, (3) Laboratorium oder (4) bei anderer Tätigkeit mit ähnlich wie bei (1) bis (3) erhöhter Infektionsgefahr. Der Versicherungsschutz bezieht sich auf Arbeitnehmerinnen und Arbeitnehmer, Selbständige – soweit nicht befreit – und Ehrenamtliche. Gesetzlich meldepflichtig ist die COVID-19-Erkrankung, meist in Verbindung mit zeitnahem SARS-CoV-2-Erregernachweis. Eine COVID-19-Erkrankung kann dann als Arbeitsunfall vorliegen, wenn sich der intensive und direkte Kontakt zu infizierten Personen nicht bestimmungsgemäß wie bei der Berufskrankheit 3101, sondern anderweitig situativ aus der versicherten Tätigkeit ergibt.
Tri-directional piezoelectric energy harvester based on U-shaped beam-pendulum structure
Authors: Mo Shuting , Liu Yan , Shang Siyao , Wang Hai , Yang Keyuan 
Published: January 2021

This Note proposed a multi-direction piezoelectric energy harvester with a wide bandwidth and low working frequency, which is distinguished by the multiple working modes of the U-shaped beam and the high capacity of the pendulum in collecting arbitrary vibrations. The structural features are evaluated by finite element simulation and verified by experiments. At least three voltage peaks are generated in the frequency range of 0 Hz–25 Hz, and favorable harvesting consistency in different directions is achieved. The designed structure is adaptable in collecting energy from arbitrary vibration in ambient environments.
Using R2L pedagogy in teaching practical writing to non-Chinese speaking students in Hong Kong
Authors: Shum Mark Shiu-kee , Shi Dan 
Published: January 2021

AbstractSince Hong Kong handover, the language policy in Hong Kong shifts from diglossic bilingualism to bi-literacy and trilingualism policy, balancing the status of English and Chinese with the mother tongue education policy. This policy shift has inadvertently impacted non-Chinese speaking (NCS) students’ enrollment, whose limited mastery of Chinese language prevents them from the mainstream schooling. Faced with this ethnically diverse and multilingual population, Applied Learning Chinese (ApL(C)) motivating practical reading and writing in an applied learning context was proposed by Hong Kong Education Bureau as an alternative for second language education. This study examines the effectiveness of “Reading to Learn, Learning to Write, R2L” pedagogy (Rose, 2012) in teaching Chinese practical writing to NCS students in Hong Kong with pedagogic interventions and Systemic Functional analytical perspective. Semi-structured interviews were conducted to perceive students’ learning experiences with R2L pedagogy. The finding suggests an increased meta-linguistic awareness of genre-specific writings after interventions to be empowered with a voice against social inequity and be empathized with humanistic reflections.
High spin expansion for null geodesics
Authors: Li Peng-Cheng , Guo Minyong , Chen Bin 
Published: January 2021

Abstract
We consider the high spin expansion for the null geodesics in the Kerr spacetime. We expand the null geodesic equation successively to higher orders in deviation from extremality. Via the method of matched asymptotic expansion, the radial integrals are obtained analytically. It turns out that the analytic expressions are very sensitive to the value of the shifted Carter constant q. We show that for a large q, the analytic expressions can be used to study observational electromagnetic signatures for astrophysical black holes like M87*. However, for a small q, the high spin expansion method can only be applied to (near-) extreme black holes.
Observing the polarization of cosmic-ray muons in student physics laboratory
Authors: Xu Jisi , Chu Anjun , Yuan Zi , Song Xinliang , Cheng Tianle , Yi Han , Wang Yijie , Chang Ying , Zhang Zhao , Xiao Zhigang 
Published: January 2021

Abstract
An undergraduate-level student experiment has been designed and implemented to measure the forward–backward asymmetry of the decay of the cosmic-ray muons, offering a pedagogical view to the parity violation in weak interactions. The detector system consists of six plastic scintillators installed vertically in row. The backward–forward asymmetry of the decay e−  and  e+ with respect to the muon motion direction is correlated with the incident depth of the muon stopped in the scintillator. MC simulations have been carried out in order to better interpret the data and optimize the data analysis. The forward–backward asymmetry of 0.051 ± 0.027 is deduced for the decay of cosmic-ray muons in the energy range being studied. The results are consistent with the picture of parity violation in weak interactions. The experiment can be constructed by the senior undergraduate students under the guidance of the course teacher.
Convergence of proximal gradient algorithm in the presence of adjoint mismatch
*
Authors: Chouzenoux Emilie , Pesquet Jean-Christophe , Riddell Cyril , Savanier Marion , Trousset Yves 
Published: January 2021

Abstract
We consider the proximal gradient algorithm for solving penalized least-squares minimization problems arising in data science. This first-order algorithm is attractive due to its flexibility and minimal memory requirements allowing to tackle large-scale minimization problems involving non-smooth penalties. However, for problems such as x-ray computed tomography, the applicability of the algorithm is dominated by the cost of applying the forward linear operator and its adjoint at each iteration. In practice, the adjoint operator is thus often replaced by an alternative operator with the aim to reduce the overall computation burden and potentially improve conditioning issues. In this paper, we propose to analyze the effect of such an adjoint mismatch on the convergence of the proximal gradient algorithm in an infinite-dimensional setting, thus generalizing the existing results on PGA. We derive conditions on the step-size and on the gradient of the smooth part of the objective function under which convergence of the algorithm to a fixed point is guaranteed. We also derive bounds on the error between this point and the solution to the original minimization problem. We illustrate our theoretical findings with two image reconstruction tasks in computed tomography.
Bending behavior and its effect on switching performance of an all-optical switch
Authors: Wang K F , Wang B L , Zheng L , Zhang Y , Zhang C W 
Published: January 2021

Abstract
The all-optical switch is one of the key elements of all-optical high speed information networks and computing systems. Their bending behavior, actuated by optical gradient forces, dramatically influences their switching performance and is therefore the research topic of this paper. The coupled behavior between optical gradient forces and the bending deflection is taken into account in the present model. The effects of the effective refractive index and the stretching induced by bending are included and their influences on the resonance wavelength shift of the signal light are discussed. Results show that the resonance wavelength shift increases almost linearly at first, and then increases suddenly as the circulating power increases. The resonance wavelength shift increases as the central angle of the suspended part increases, while it decreases with the initial gap. The present theoretical model may be helpful when designing all-optical switches.
Flavor, temperature and magnetic field dependence of the QCD phase diagram: magnetic catalysis and its inverse
Authors: Ahmad Aftab , Bashir Adnan , Bedolla Marco A , Cobos-Martínez J J 
Published: January 2021

Abstract
We study dynamical chiral symmetry breaking for quarks in the fundamental representation of SU(N
c) for the N
f number of light quark flavors. We also investigate the phase diagram of quantum chromodynamics at finite temperature T and/or in the presence of a constant external magnetic field eB. The unified formalism for this analysis is provided by a symmetry-preserving Schwinger–Dyson equation treatment of a vector × vector contact interaction model which encodes several well-established features of quantum chromodynamics to mimic the latter as closely as possible. Deconfinement and chiral symmetry restoration are triggered above a critical value of N
f at T = 0 = eB. On the other hand, increasing temperature itself screens strong interactions, thus ensuring that a smaller value of N
f is sufficient to restore chiral symmetry at higher temperatures. We also observe the well-known phenomenon of magnetic catalysis for a strong enough magnetic field. However, we note that if the effective coupling strength of the model decreases as a function of magnetic field, it can trigger inverse magnetic catalysis in a certain window of this functional dependence. Our model allows for the simultaneous onset of dynamical chiral symmetry breaking and confinement for each case. Qualitative as well as quantitative predictions of our simple but effective model are in reasonably satisfactory agreement with lattice results and other reliable and refined predictions based upon intricate continuum studies of quantum chromodynamics.
Impact of noble-gas filler atoms on the lattice thermal conductivity of CoSb3 skutterudites: first-principles modelling
Authors: Tang Jianqin , Skelton Jonathan M 
Published: January 2021

Abstract
We present a systematic first-principles modelling study of the structural dynamics and thermal transport in CoSb3 skutterudites with a series of noble-gas filler atoms. Filling with chemically-inert atoms provides an idealised model for isolating the effects of the fillers from the impact of redox changes to the host electronic structure. A range of analysis techniques are proposed to estimate the filler rattling frequencies, to quantify the separate impacts of the fillers on the phonon group velocities and lifetimes, and to show how changes to the phonon spectra and interaction strengths lead to suppressed lifetimes. The noble-gas fillers are found to reduce the thermal conductivity of the CoSb3 framework by up to 15% primarily by suppressing the group velocities of low-lying optic modes. The filler rattling frequencies are determined by a detailed balance of increasing atomic mass and stronger interactions with the framework, and are found to be a good predictor of the impact on the heat transport. Lowering the rattling frequency below ∼1.5 THz by selecting heavy fillers that interact weakly with the framework is predicted to lead to a much larger suppression of the thermal transport, by inducing avoided crossings in the acoustic-mode dispersion and facilitating enhanced scattering and a consequent large reduction in phonon lifetimes. Approximate rattling frequencies determined from the harmonic force constants may therefore provide a useful metric for selecting filler atoms to optimise the thermal transport in skutterudites and other cage compounds such as clathrates.
Development of skeletal systems for ICRP pediatric mesh-type reference computational phantoms
Authors: Choi Chansoo , Shin Bangho , Yeom Yeon Soo , Han Haegin , Ha Sangseok , Moon Sungho , Son Gahee , Nguyen Thang Tat , Kim Chan Hyeong , Chung Beom Sun , Bolch Wesley E 
Published: January 2021

Abstract
In 2016, the International Commission on Radiological Protection (ICRP) launched Task Group 103 (TG 103) for the explicit purpose of developing a new generation of adult and pediatric reference computational phantoms, named ‘mesh-type reference computational phantoms (MRCPs)’, that can overcome the limitations of voxel-type reference computational phantoms (VRCPs) of ICRP Publications 110 and 143 due to their finite voxel resolutions and the nature of voxel geometry. After completing the development of the adult MRCPs, TG 103 has started the development of pediatric MRCPs comprising 10 phantoms (male and female versions of the reference newborn, 1-year-old, 5-year-old, 10-year-old, and 15-year-old). As part of the TG 103 project, within the present study, the skeletal systems, one of the most important and complex organ systems of the body, were developed for each phantom age and sex. The developed skeletal systems, while closely preserving the original bone topology of the pediatric VRCPs, present substantial improvements in the anatomy of complex and/or small bones. In order to investigate the dosimetric impact of the developed skeletons, the average absorbed doses and the specific absorbed fractions for radiosensitive skeletal tissues (i.e. active marrow and bone endosteum) were computed for some selected external and internal exposure cases, which were then compared with those calculated with the skeletons of pediatric VRCPs. The comparison result showed that the dose values of the pediatric MRCPs were generally similar to those of the pediatric VRCPs for highly penetrating radiations (e.g. photons >200 keV); however, for weakly penetrating radiations (e.g. photons ⩽200 keV and electrons), significant differences up to a factor of 140 were observed.
High-precision time delay estimation of narrowband radio signal by PHAT-LSTM
Authors: Yao Shunyu , Meng Qiao , Chen Congyan , Tariq Irfan , Zhou Chenye , Liu Wei 
Published: January 2021

Abstract
In this article, a novel method for high-precision time-delay estimation (TDE) of narrow-band signals is proposed. It is based on a cross-correlation function, phase spectrum, long short-term memory (LSTM) artificial neural network to unwrap the phase transform (PHAT) spectrum of the cross-correlation function. The PHAT-LSTM architecture consists of three parts. The first part is a wrapping parameter estimator (WPE) used to estimate the wrapping parameter of the base-band phase spectrum. The second part, a wrapping classifier (WCF), is a single output network used to compensate the drawbacks of the WPE. The third part, a synthesize and fine estimator, synthesizes the information from the WPE and WCF to unwrap the phase and estimate the delay according to the phase-delay model. The input of the PHAT-LSTM are fast Fourier transforms of snapshot data from two receiving channels. In addition, the dimension of the input signals was dramatically decreased compared with other deep learning-based TDE methods. Simulation results show that the root mean square error (RMSE) of the PHAT-LSTM is decreased in low signal-to-noise ratio (SNR) compared with traditional TDE methods. When the SNR = 10 dB or 0 dB, the RMSE of TDE was about ten times smaller than that of traditional methods.
Laser shock pressing of silver nanowires on flexible substrates to fabricate highly uniform transparent conductive electrode films
Authors: Noh Jihun , Kim Dongsik 
Published: January 2021

AbstractLarge surface roughness, wire-to-wire junction resistance, and poor adhesion strength of percolated silver nanowire films on polymer substrates are critical issues responsible for low shunt resistance, electron concentration, and thermal damage, resulting in the occurrence of dark spots and damage to flexible electronic devices. Therefore, the fabrication of transparent conductive electrode (TCE) thin films with high surface smoothness and enhanced film properties without the aforementioned problems is essential. Herein, we propose an innovative method to mechanically join silver nanowires on heat-sensitive polymer substrates using a laser-induced shock pressure wave generated by laser ablation of a sacrificial layer. The physical joining mechanism and film properties, that is, sheet resistance, transmittance, adhesion strength, and flexibility, were experimentally analyzed. When a high laser shock pressure was applied to the silver nanowires, plastic deformation occurred; thus, a sintered network film was fabricated through solid-state atomic diffusion at the nanowire junctions. Under optimal process conditions, the sintered films showed high resistance to the adhesion tape test (R/R0 = 1.15), a significantly reduced surface roughness less than 6 nm, and comparable electrical conductivity (8 ± 2Ω·sq−1) and visible transmittance (84% ± 3%) to typical joining methods. Consequently, this work demonstrates that the laser-induced shock pressing technique has strong potential for the production of TCE metal films on heat-sensitive flexible substrates with film properties superior to those of films produced by conventional methods.
Flexible capacitive sensor based on 2D-titanium dioxide nanosheets/bacterial cellulose composite film
Authors: Sriphan Saichon , Charoonsuk Thitirat , Khaisaat Supharada , Sawanakarn Oubonwan , Pharino Utchawadee , Phunpruch Saranya , Maluangnont Tosapol , Vittayakorn Naratip 
Published: January 2021

Abstract
In this paper, titanium dioxide nanosheets (Ti0.91O2 NSs) were incorporated into bacterial cellulose (BC) film for dielectric property tuning while maintaining the flexibility of the resulting composite paper. By taking advantage of the improved dielectric constant, the nanosheets/BC composites were employed as capacitive sensors. The fabricated devices showed the highest sensing performance of ∼2.44 × 10−3 kPa−1 from 0 to 30 N when incorporating as little as 3 vol% of Ti0.91O2 NSs (or ∼2 wt% Ti). Stable operation and high robustness of the sensor were demonstrated, where simple human motions could be efficiently monitored. This study provided a route for preparing flexible and low-cost BC composite paper for capacitive sensor. The strategy for enhancing the dielectric properties as well as sensing performances of the BC demonstrated herein will be essential for the future development of biocompatible, low-cost, and eco-friendly wearable electronics.
One-step synthesis of blue–green luminescent carbon dots by a low-temperature rapid method and their high-performance antibacterial effect and bacterial imaging
Authors: Zhao Dan , Zhang Rui , Liu Xuemei , Huang Xianju , Xiao Xincai , Yuan Lin 
Published: January 2021

Abstract
Due to the global infection problem caused by the abuse of antibiotics, the preparation of novel antibacterial nanomaterials is a key and basic requirement for applications in antibacterial and bacterial imaging fields. This paper reports the one-step preparation of blue–green-emitting carbon dots (CDs) under low temperature (80 °C) with glucose as the carbon source, citric acid as the dehydrating agent, and polyethyleneimine as the nitrogen source. Through inhibition zone tests and minimum inhibitory concentration (MIC) experiments, the inhibitory abilities of prepared CDs against various microorganisms, including gram-positive bacteria, gram-negative bacteria and fungi, were compared. It is worth mentioning that the MIC of CDs against Staphylococcus aureus reaches 4.7 μg ml−1, and the CDs exhibit excellent biocompatibility. Moreover, studies on visual-treatment therapy, in which infection treatment can be performed at the same time as bacterial imaging, with the prepared functional antibacterial CDs based on fluorescence confocal imaging would be beneficial to their promising future in medical and biological fields.