bluuebunny/crossref_metadata_2025_split huggingface dataset:
Post-swim oxygen consumption: assessment methodologies and kinetics analysis
Authors: Monteiro Ana Sofia , Carvalho Diogo D , Azevedo Rui , Vilas-Boas João Paulo , Zacca Rodrigo , Fernandes Ricardo J 
Published: August 2020

Abstract

Objective: This study aimed at comparing different recovery-based methods to assess the highest exercise oxygen uptake value (

V
˙

O2peak) when swimming at low-moderate, heavy and severe intensities. Complementarily, the different recovery curve kinetics were analysed. Approach: Eighteen competitive swimmers performed a 5 × 200 m front crawl intermittent protocol (0.05 m · s−1 increments and 3 min intervals), with respiratory gas exchange being continuously measured breath-by-breath during and post-exercise using a portable gas analyser. The directly determined

V
˙

O2peak (

V
˙

O2dir) was compared with the values obtained by linear and exponential backward extrapolations (of different intervals) and the recovery curve mathematical modelling. Main results:

V
˙

O2dir rose with intensity increase: 41.96 ± 6.22, 46.36 ± 6.89 and 50.97 ± 7.28 ml · kg−1 min−1 for low-moderate, heavy and severe swims. Linear and exponential regressions applied to the first 20 s of recovery presented the

V
˙

O2peak values closest to

V
˙

O2dir at low-moderate (42.80 ± 5.54 vs 42.88 ± 5.58 ml kg−1 min−1), heavy (47.12 ± 4.91 vs 47.48 ± 5.09 ml kg−1 min−1) and severe intensity domains (51.24 ± 6.89 vs 53.60 ± 8.54 ml kg−1 · min−1, respectively; r = 0.5–0.8, p < 0.05). The mono-exponential function was the best fit at low-moderate and heavy intensities, while the bi-exponential function better characterized the severe exercise domain (with a slow component amplitude, time delay and time constant of 6.2 ± 2.3 ml kg−1 min−1, 116.6 ± 24.3 and 39.9 ± 15.2 s, respectively). Significance: The backward extrapolation of the first 20 s of recovery is the best method to assess the

V
˙

O2peak for a large spectrum of swimming intensities. Complementarily, intensity increases imply different recovery curve kinetics, particularly a mono-exponential behaviour for low-moderate and heavy exertions and a bi-exponential dynamics for severe paces.
Depression evaluation based on prefrontal EEG signals in resting state using fuzzy measure entropy
Authors: Chen Feifei , Zhao Lulu , Li Baimin , Yang Licai 
Published: August 2020

Abstract

Objective: Depression is a mental disorder that causes emotional changes and even suicide. However, there is still a lack of objective physiological data to support current clinical depression diagnosis. Accurate computer-aided diagnosis systems are becoming more and more crucial and urgent for future depression diagnosis. The purpose of this study is to analyze the electroencephalogram (EEG) regularity of depression using fuzzy measure entropy (FMEn), and thus to explore its role in the computer-aided diagnosis of depression. Approach: Three-channel EEG signals among 35 subjects (divided into two groups according to the severity of the disease) were recorded in this study. First, the frontal delta, theta, alpha and beta frequency bands were extracted after preprocessing, and the sample entropy (SEn) and the FMEn were calculated. Then, the difference between the two groups and the correlation between the entropy values and the Hamilton Depression Rating Scale scores were analyzed using statistical analysis. Finally, the results of FMEn were compared with those of SEn. Main results: A better statistically significant difference between the two groups using FMEn was revealed, with p < 0.01 in the theta and alpha bands. In terms of SEn, only SEn_Fp2 in the delta band, SEn_Fp2 in the theta band and SEn_Fp1 in the alpha band performed better, showing significant differences with p = 0.0006, p = 0.002 and p = 0.0114. Significance: These findings suggest that frontal EEG signal complexity analysis with depression using FMEn might be more sensitive than that using SEn. FMEn could be considered as a promising biomarker for future clinical depression detection.
Low-temperature deposition of 2D SnS nanoflakes on PET substrates for flexible photodetectors with broadband response
Authors: Dong Aodi , Tian Tian , Zhao Hongxiao , Li Shasha , Deng Shuwen , Song Xiaohui , Yan Yong , Xia Congxin , Li Jingbo 
Published: August 2020

Abstract
Flexible photodetectors based on two-dimensional (2D) materials hold the promise to open up an unprecedented era for wearable optoelectronic systems. However, there is a major challenge of the inability to directly deposit 2D materials on polymeric substrates due to their high growth temperature. Here, we demonstrate a novel low-cost method to directly fabricate SnS nanoflakes on the poly-ethylene terephthalate substrates. Moreover, the flexible photodetectors based on SnS nanoflakes feature broadband spectral responses from 355 nm to 1550 nm. The responsivity and detectivity can approach up to 1.28 × 103 A W−1 and 3.02 × 1011 Jones, respectively, under the ultraviolet laser of 355 nm. The devices also exhibit excellent NIR photodetection with a speciﬁc responsivity of 69 A W−1 towards the 1550 nm regime. Our research represents an important step toward scalable fabrication of the SnS nanoflakes and this method may pave a path for the future commercialization of flexible broadband optoelectronic devices.
High voltage trench insulated gate bipolar transistor with MOS structure for self-adjustable hole extraction
Authors: Zhao Yishang , Li Zehong , Peng Xin , Yang Yang , Zeng Xiao , Ren Min , Zhang Jinping , Gao Wei , Zhang Bo 
Published: August 2020

Abstract
In this letter, a novel high voltage trench insulated gate bipolar transistor (IGBT) with MOS structure for self-adjustable hole extraction (MOS-SH-IGBT) is proposed. It features the adjustable hole path (AHP) region controlled by the MOS structure. The AHP region stores holes during on-state, extracts holes swiftly to reduce switching loss during turn-off and provides an extra hole path to avoid latch-up during short-circuit. Because of shielding effects of the AHP region, MOS-SH-IGBT could also increase breakdown voltage (BV) and decrease Miller capacitance. Based on simulated results, the BV of the proposed device is increased by 10% compared with the conventional separate floating P-base IGBT. Furthermore, the Miller capacitance and switching loss of MOS-SH-IGBT are decreased by 64% and 29%, respectively. As for the same E
on of 117.3mJ cm−2, the dIce/dt of the MOS-SH-IGBT is decreased by 38.7%, and for the same E
off of 64.1mJ cm−2, the |dIce/dt| is decreased by 23.4%, which realizes lower EMI noise.
Dynamic noninvasive imaging through turbid media under low signal-noise-ratio
Authors: Yuan Yuan , Chen Hui 
Published: August 2020

Abstract
In turbid media, scattering of light scrambles information of the incident beam and represents an obstacle to optical imaging. Noninvasive imaging through opaque layers is especially challenging for reliable image reconstruction and dynamic objects. We here propose a solution to these problems: rather than using the full point-spread function or its Fourier transform (optical transfer function, OTF), the wave distortions in scattering layers can be characterized and diffraction-limited imaging performed using only the phase of OTF. Based on this understanding, we develop a method that exploits the redundant information from multiple measurements, which reliably yields OTF phases within several iterations. This method enables noninvasive imaging through turbid media with low signal-to-noise ratios in the measurements, which is not possible with previous methods. We then demonstrate noninvasive video imaging of a moving object hidden between scattering layers at 25–200 Hz. This imaging approach may inspire many other applications in scattering materials.
An ultra-compact x-ray free-electron laser
Authors: Rosenzweig J B , Majernik N , Robles R R , Andonian G , Camacho O , Fukasawa A , Kogar A , Lawler G , Miao Jianwei , Musumeci P , Naranjo B , Sakai Y , Candler R , Pound B , Pellegrini C , Emma C , Halavanau A , Hastings J , Li Z , Nasr M , Tantawi S , Anisimov P. , Carlsten B , Krawczyk F , Simakov E , Faillace L , Ferrario M , Spataro B , Karkare S , Maxson J , Ma Y , Wurtele J , Murokh A , Zholents A , Cianchi A , Cocco D , van der Geer S B 
Published: August 2020

Abstract
In the field of beam physics, two frontier topics have taken center stage due to their potential to enable new approaches to discovery in a wide swath of science. These areas are: advanced, high gradient acceleration techniques, and x-ray free electron lasers (XFELs). Further, there is intense interest in the marriage of these two fields, with the goal of producing a very compact XFEL. In this context, recent advances in high gradient radio-frequency cryogenic copper structure research have opened the door to the use of surface electric fields between 250 and 500 MV m−1. Such an approach is foreseen to enable a new generation of photoinjectors with six-dimensional beam brightness beyond the current state-of-the-art by well over an order of magnitude. This advance is an essential ingredient enabling an ultra-compact XFEL (UC-XFEL). In addition, one may accelerate these bright beams to GeV scale in less than 10 m. Such an injector, when combined with inverse free electron laser-based bunching techniques can produce multi-kA beams with unprecedented beam quality, quantified by 50 nm-rad normalized emittances. The emittance, we note, is the effective area in transverse phase space (x, p

x
/m
e
c) or (y, p

y
/m
e
c) occupied by the beam distribution, and it is relevant to achievable beam sizes as well as setting a limit on FEL wavelength. These beams, when injected into innovative, short-period (1–10 mm) undulators uniquely enable UC-XFELs having footprints consistent with university-scale laboratories. We describe the architecture and predicted performance of this novel light source, which promises photon production per pulse of a few percent of existing XFEL sources. We review implementation issues including collective beam effects, compact x-ray optics systems, and other relevant technical challenges. To illustrate the potential of such a light source to fundamentally change the current paradigm of XFELs with their limited access, we examine possible applications in biology, chemistry, materials, atomic physics, industry, and medicine—including the imaging of virus particles—which may profit from this new model of performing XFEL science.
Energy correction based on fluorescence attenuation of DAMPE
Authors: Wu Li-Bo , Zhang Yun-Long , Zhang Zhi-Yong , Wei Yi-Feng , Wen Si-Cheng , Dai Hao-Ting , Liu Cheng-Ming , Wang Xiao-Lian , Xu Zi-Zong , Huang Guang-Shun 
Published: August 2020

Abstract
The major scientific goals of the DArk Matter Particle Explorer (DAMPE) are to study cosmic-ray electrons (including positrons) and gamma rays from 5 GeV to 10 TeV and nuclei from Z = 1 to 26 up to 100 TeV. The deposited energy measured by the Bismuth Germanate Oxide (BGO) calorimeter of DAMPE is affected by fluorescence attenuation in BGO crystals that are 600 mm long. In this work, an in-orbit attenuation calibration method is reported, and energy correction of the sensitive detector unit of the BGO calorimeter is also presented.
Long-period eclipsing binaries: towards the true mass-luminosity relation. I. the test sample, observations and data analysis
Authors: Kniazev Alexei Yu. , Malkov Oleg Yu. , Katkov Ivan Yu. , Berdnikov Leonid N. 
Published: August 2020

Abstract
The mass-luminosity relation is a fundamental law of astrophysics. We have suggested that the currently used mass-luminosity relation is not correct for the M/M
⊙ > 2.7 range of mass since it was created utilizing double-lined eclipsing binaries, where the components are synchronized and consequently change each other’s evolutionary path. To exclude this effect, we have started a project to study long-period massive eclipsing binaries in order to construct radial velocity curves and determine masses for the components. We outline our project and present the selected test sample together with the first HRS/SALT spectral observations and the software package, Fitting Binary Stars (fbs), that we developed for the analysis of our spectral data. As the first result, we present the radial velocity curves and best-fit orbital elements for the two components of the FP Car binary system from our test sample.
Investigation of the parameters of spiral pattern in galaxies: the arm width
Authors: Mosenkov Aleksandr , Savchenko Sergey , Marchuk Alexander 
Published: August 2020

Abstract
In this work, we determine the parameters of spiral structure for a sample of face-on spiral galaxies. In practice, the solution to this problem is a hard task because of the diversity of observed characteristics associated with spiral structure, such as the number of arms, their shape, arm contrast, etc. We study spiral structure in galaxies based on an analysis of photometric cuts perpendicular to the arm direction. The method is based on an approximation of these slices with an analytical function and derivation of the parameters of spiral structure (arm width, asymmetry, pitch angle) using the fitted parameters from this approximation. The algorithm has been applied to a sample of 155 galaxies selected from the Sloan Digital Sky Survey in different passbands. In this paper, we only consider the results on arm width: most spirals exhibit an increase in their width with galactocentric distance. Only 14 per cent of galaxies in our sample show an opposite trend or have an almost constant arm width at all radii.
Influence of the convective mixing-length parameter α on the chemical abundances in the case of metal-poor giant HD 122563
Authors: Song Nan , Alexeeva Sofya , Zhao Gang 
Published: August 2020

Abstract
One-dimensional (1D) model atmospheres are still the most commonly used tool for the determination of stellar chemical composition. Convection in the model is usually treated by mixing-length theory (MLT). The mixing-length parameter α is generally calibrated from the Sun and applied to all other stars. The metal-poor giant, HD 122563, is an important benchmark star to test stellar atmosphere and interior physics. We investigate the influence of the convection mixing-length parameter α on the determination of chemical abundances of Na, Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Co, Ni, Sr, Y, Zr and Ba in the case of HD 122563, taking advantage of a high resolution and high signal-to-noise ratio HARPS spectrum. The abundance discrepancies Δ[X/H] that occur due to α variation rarely exceed 0.05 dex and most are less than 0.03 dex. We calculate the discrepancy Δ[X/H] using a line-by-line differential analysis. The abundance discrepancies do not have direct relation with either line strength or the excitation potential. For 1D stellar atmospheric analysis of HD 122563, the accuracy of abundance determination does not strongly depend on the choice of mixing-length parameter α (causing average discrepancies of < 0.03 dex), while the uncertainties in the effective temperature and surface gravity play a more important role.
Neutrino spin-flavor oscillations in solar environment
Authors: Joshi Sandeep , Jain Sudhir R. 
Published: August 2020

AbstractWe study the phenomenon of neutrino spin-flavor oscillations due to solar magnetic fields. This allows us to examine how significantly the electron neutrinos produced in the solar interior undergo a resonant spin-flavor conversion. We construct analytical models for the solar magnetic field in all the three regions of the Sun. Neutrino spin-flavor oscillations in this magnetic field are examined by studying the level crossing phenomenon and comparing the two cases of zero and non-zero vacuum mixing respectively. Results from the Borexino experiment are used to place an upper limit on the magnetic field in the solar core. Related phenomena such as effects of matter on neutrino spin transitions and differences between Dirac and Majorana transitions in the solar magnetic fields are also discussed.
Detection of hydroxyacetone in protostar IRAS 16293-2422 B
Authors: Zhou Yan , Quan Dong-Hui , Zhang Xia , Qin Sheng-Li 
Published: August 2020

Abstract
Hydroxyacetone (CH3COCH2OH) is one of the smallest molecules that contain both hydroxyl and carbonyl group on neighboring carbon atoms. This steric configuration is characteristic of saccharides and determines their biochemical activity. The attempt to search for hydroxyacetone toward the massive star formation region Sagittarius B2(N) was unsuccessful. Here we report the first detection of CH3COCH2OH in the solar-type protostar IRAS 16293–2422 B, using the Atacama Large Millimeter Array science verification data at Band 4. In a total of 11 unblended transitions of CH3COCH2OH with upper level energies ranging from 86 to 246 K are identified. From our local thermodynamic equilibrium analysis, we derived that the rotational temperature of CH3COCH2OH is 160±21 K and the column density is (1.2±1.0) ×1016 cm−2, which results in a fractional abundance of 7×10−10 with respect to molecular hydrogen. In this work, we present the identification of CH3COCH2OH in IRAS 16293–2422 B and propose a simple formation mechanism. The unambiguous identification of hydroxyacetone may provide the basis for future study of the origin and evolution of saccharides in the interstellar medium.
Inversion of Venus internal structure based on geodetic data
Authors: Xiao Chi , Li Fei , Yan Jian-Guo , Hao Wei-Feng , Harada Yuji , Ye Mao , Barriot Jean-Pierre 
Published: August 2020

Abstract
Understanding the internal structure of Venus promotes the exploration of the evolutionary history of this planet. However, the existing research concerning the internal structure of Venus has not used any inversion methods. In this work we employed an inversion method to determine the internal structure of Venus using observational or hypothetical geodetic data; these data include mass, mean radius, mean moment of inertia and second degree tidal Love number k
2. To determine the core state of Venus, we created two models of Venus, an isotropic 3-layer model with entire liquid core and an isotropic 4-layer model with liquid outer core and a solid inner core, assuming that the interior of Venus is spherically symmetric and in hydrostatic equilibrium. A series of the sensitivity analysis of interior structure parameters to the geodetic data considered in here shows that not all of the parameters can be constrained by the geodetic data from Venus. On this basis, a Markov Chain Monte Carlo algorithm was used to determine the posterior probability distribution and the optimal values of the internal structure parameters of Venus with the geodetic data. We found that the 3-layer model is more credible than the 4-layer model via currently geodetic data. For the assumption of the 3-layer model with the k
2 = 0.295 ± 0.066, I/MR
2 = 0.33 ± 0.0165, and

ρ
¯

=
5242.7
±
2.6

kgm−3, the liquid iron-rich core of Venus has a radius of

3294

−
261

+
215

km, which suggests a larger core than previous research has indicated. The average density of the mantle and liquid core of Venus are

4101

−
375

+
325

and

11885

−
1242

+
955

kgm−3, respectively.
Age and chemical composition of the globular cluster NGC 6652
Authors: Sharina Margarita Eugene , Shimansky Vladislav Vladimirovich 
Published: August 2020

Abstract
We present the results of determination of the age, helium mass fraction (Y), metallicity ([Fe/H]), and abundances of the elements C, N, O, Na, Mg, Ca, Ti, C and Mn for the Galactic globular cluster NGC 6652. We use its medium-resolution integrated-light spectrum from the library of Schiavon and our population synthesis method to fulfill this task. We select the evolutionary isochrone and stellar mass function for our analysis, which provide the best approximation to the shapes and intensities of the observed Balmer line profiles. The determined elemental abundances, age and metallicity are characteristic of stellar populations in the Galactic Bulge.
NLTE analysis of high-resolution H-band spectra IV: neutral copper
Authors: Xu Xiao-Dong , Shi Jian-Rong , Zhang Jun-Bo , Zhou Ze-Ming 
Published: August 2020

Abstract
To obtain reliable Cu abundances with the APOGEE H-band spectra, it is important to investigate the non-local thermodynamic equilibrium (NLTE) effects on the formation of the H-band Cu I lines. In addition, the Cu atomic model needs to be tested. Based on both the high-resolution and high signal-to-noise ratio H-band spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) and optical data, we derived the LTE and NLTE copper abundances of 13 FGK sample stars with the spectral synthesis method. We find that the NLTE effects are negligible for the Cu I 16005.7Å line in the IR H-band. Consistent copper abundances within the uncertainties from these two sets of lines have been obtained, which indicates the reliability of our NLTE copper atomic model. We note that the [Cu/Fe] ratios increase with increasing metallicity when ∼ – 1.4 dex < [Fe/H] < ∼ – 0.5 dex, favoring a secondary (metallicity-dependent) copper production.
Eclipsing binary XZ CMi in a hierarchical quadruple system
Authors: Wang Zhi-Hua , Zhu Li-Ying 
Published: August 2020

Abstract
The new complete BVRcIc
light curves and spectra of the short-period eclipsing binary XZ CMi are presented. The results from the combined analysis based on the photometric and spectroscopic data show that XZ CMi is a near contact binary with the secondary component filling its critical Roche lobe while the primary filling 91% of its Roche lobe. The investigation of the O – C diagram reveals that its orbital period is continuously increasing, which is consistent with the derived configuration and caused by the mass transfer from the less massive star to the more massive one. In addition, an obvious periodic modulation with the amplitude of0.0187(±0.0016) d and a high eccentric of 0.86(±0.04) is detected, which could be the results of the light time effect as a third star with the mass no less than 0.42(±0.09) M
⊙ orbiting around the central eclipsing binary once every 95.7(±2.1) yr. Furthermore, we found a visual companion star at 2.4” east by south of this system at a much greater distance by direct image. The large third light contribution found from the light curve analysis could be well explained by the existence of the third star and the fourth visual one. The similar parallax and proper motion imply that the components of this hierarchical quadruple system might be bounded by gravitation. Spectroscopic observations for two visual components were carried out by the LAMOST and 2.16 m telescopes, respectively. Their different values of [Fe/H] suggest that they were not born from the same origin. Thus, XZ CMi system is an interesting and important target to study the formation of the multiple stars.
Effect of induced magnetic field and linear / non-linear vertical stretching sheet on mixed convection Jeffrey fluid near a stagnation-point flow through a porous medium with suction or injection
Authors: Katyayani G. , Lakshmi Devi R. 
Published: August 2020

Abstract
The present study deals with the effect of induced magnetic field on mixed convective near a stagnation point flow with linear / non-linear vertical stretching sheet of Jeffrey fluid flow through porous medium in the presence of slip flow regime. The set of governing non-linear coupled partial differential equations are transformed into a set of non-linear coupled ordinary differential equations using suitable similarity transformations, which are then solved numerically using Runge-Kutta fourth order in association with shooting technique in MATLAB. The effects of non-dimensional parameters such as Jeffrey parameter, magnetic force number, magnetic Prandtl number, magnetic parameter, suction/injection parameter, slip velocity parameter, linear or non-linearity parameter, permeability parameter, velocity ratio parameter, Prandtl number, thermal radiation parameter and Eckert number on velocity, induced magnetic field and temperature are presented graphically while the skin friction and local Nusselt number are represented numerically.