bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interpretation of frequency response analysis of power transformer based on evidence theory
Authors: Shamlou Alireza , Reza Feyzi Mohammad , Behjat Vahid 
Published: July 2019

Power transformers are one of the key components of power systems. Therefore, they must be operated efficiently to obtain satisfactory system performance, since any distortion or failure in power transformer structures may cause drastic damages. In order to detect deficiencies in power transformers, various methods are utilised. Frequency response analysis (FRA) is one of the most well‐known methods used for fault detection in power transformers. However, the interpretation of FRA results is subjective, and depends primarily on the opinion of a human expert. In other words, there is no comprehensive, accepted and standardised method to interpret FRA results. Subsequently, fault detection based on FRA is prone to error. In this study, a new mathematical approach is used to interpret the frequency response of power transformers based on evidence theory method. This method is more accurate and less computationally burdensome compared to conventional methods. Simulations are implemented on an operating 125 MVA, 230/132/20 kV autotransformer using finite‐element method and the results are compared to the corresponding FRA results of the same autotransformer in order to evaluate the proposed method. The obtained results indicate the efficiency of the proposed method in detecting probable faults of transformer windings through analysing the FRA results.
Temporal and frequency‐domain assessment of thermal and electrical ageing of mineral and vegetable oils
Authors: Chetibi Fouzia , Moulai Hocine , Idir Omar 
Published: July 2019

This study focuses on the effect of accelerated thermal and electrical ageing on the dielectric properties of two vegetable oils (olive and soya oils) and a mineral oil which are thermally aged in sealed bottles at 110°C for durations up to 720 h and electrically submitted up to 2500 low‐energy discharges under DC voltage. The investigated properties are the real part of the complex relative permittivity, dissipation factor and conductivity in a large frequency range (20 Hz–10 MHz) using frequency domain spectroscopy. This study also discusses the discharge currents generated in these oils and their corresponding fast Fourier transforms followed by power spectral density analysis. The electrical discharges are applied to the oil samples in a plane–plane configuration electrodes and 2.5 mm gap under DC voltage. The frequency‐domain investigated descriptors are: maximum peak, mean value, rms value, peak factor, variance and standard deviation of magnitude spectrum, in addition to the resonance and bandwidth frequency of discharge currents. Furthermore, the spectrograms of these discharge currents are presented, illustrating how the frequency composition and the intensity of each frequency change with time.
Massive star cluster formation and evolution in tidal dwarf galaxies
Authors: Fensch Jérémy , Duc Pierre-Alain , Boquien Médéric , Elmegreen Debra M. , Elmegreen Bruce G. , Bournaud Frédéric , Brinks Elias , de Grijs Richard , Lelli Federico , Renaud Florent , Weilbacher Peter M. 
Published: July 2019

Context. The formation of globular clusters remains an open debate. Dwarf starburst galaxies are efficient at forming young massive clusters with similar masses as globular clusters and may hold the key to understanding their formation.
Aims. We study star cluster formation in a tidal debris, including the vicinity of three tidal dwarf galaxies, in a massive gas-dominated collisional ring around NGC 5291. These dwarfs have physical parameters that differ significantly from local starbursting dwarfs. They are gas rich, highly turbulent, their gas metallicity is already enriched up to half solar values, and they are expected to be free of dark matter. The aim is to study massive star cluster formation in this as yet unexplored type of environment.
Methods. We used imaging from the Hubble Space Telescope using broadband filters that cover the wavelength range from the near-ultraviolet to the near-infrared. We determined the masses and ages of the cluster candidates by using the spectral energy distribution-fitting code CIGALE. We considered age-extinction degeneracy effects on the estimation of the physical parameters.
Results. We find that the tidal dwarf galaxies in the ring of NGC 5291 are forming star clusters with an average efficiency of ∼40%, which is similar to blue compact dwarf galaxies. We also find massive star clusters for which the photometry suggests that they were formed at the very birth of the tidal dwarf galaxies. These clusters have survived for several hundred million years. Therefore our study shows that extended tidal dwarf galaxies and compact clusters may be formed simultaneously. In the specific case observed here, the young star clusters are not massive enough to survive for a Hubble time. However, it may be speculated that similar objects at higher redshift, with a higher star formation rate, might form some of the long-lived globular clusters.
Exploring the innermost dust formation region of the oxygen-rich AGB star IK Tauri with VLT/SPHERE-ZIMPOL and VLTI/AMBER
Authors: Adam C. , Ohnaka K. 
Published: July 2019

Context. Low- and intermediate-mass stars on the asymptotic giant branch (AGB) are known to be prevalent dust providers to galaxies, replenishing the surrounding medium with molecules and dust grains. However, the mechanisms responsible for the formation and acceleration of dust in the cool extended atmospheres of AGB stars are still open to debate.
Aims. We present visible polarimetric imaging observations of the oxygen-rich AGB star IK Tau obtained with the high-resolution polarimetric imager VLT/SPHERE-ZIMPOL at post-maximum light (phase 0.27) as well as high-spectral resolution long-baseline interferometric observations with the AMBER instrument at the Very Large Telescope Interferometer (VLTI). We aim to spatially resolve the dust and molecule formation regions, and to investigate their physical and chemical properties within a few stellar radii of IK Tau.
Methods. IK Tau was observed with VLT/SPHERE-ZIMPOL at three wavelengths in the pseudo-continuum (645, 748, and 820 nm), in the Hα line at 656.3 nm, and in the TiO band at 717 nm. The VLTI/AMBER observations were carried out in the wavelength region of the CO first overtone lines near 2.3 μm with a spectral resolution of 12 000.
Results. The excellent polarimetric imaging capabilities of SPHERE-ZIMPOL have allowed us to spatially resolve clumpy dust clouds at 20–50 mas from the central star, which corresponds to 2–5 R⋆ when combined with a central star’s angular diameter of 20.7 ± 1.53 mas measured with VLTI/AMBER. The diffuse, asymmetric dust emission extends out to ~73 R⋆. We find that the TiO emission extends to 150 mas (15 R⋆). The AMBER data in the individual CO lines also suggest a molecular outer atmosphere extending to ~1.5 R⋆. The results of our 2D Monte Carlo radiative transfer modelling of dust clumps suggest that the polarized intensity and degree of linear polarization can be reasonably explained by small-sized (0.1 μm) grains of Al2O3, MgSiO3, or Mg2SiO4 in an optically thin shell (τ550 nm = 0.5 ± 0.1) with an inner and outer boundary radius of 3.5 R⋆ and ≳25 R⋆, respectively. The observed clumpy structures can be reproduced by a density enhancement of a factor of 3.0 ± 0.5. However, the model still predicts the total intensity profiles to be too narrow compared to the observed data, which may be due to the TiO emission and/or grains other than homogeneous, filled spheres.
Conclusions. IK Tau’s mass-loss rate is 20–50 times higher than the previously studied AGB stars W Hya, R Dor, and o Cet. Nevertheless, our observations of IK Tau revealed that clumpy dust formation occurs close to the star as seen in those low mass-rate AGB stars.
Downregulation of RPS15A by miR-29a-3p attenuates cell proliferation in colorectal carcinoma
Authors: Zheng Zilei , Cui Haitao , Wang Yi , Yao Weilong 
Published: July 2019

ABSTRACT
miR-29a-3p has been reported to function as a tumor suppressor in several cancers. However, the biological function role of miR-29a-3p in colorectal carcinoma (CRC) has not been well investigated. In this study, we found that miR-29a-3p was at lower level expression in CRC tissues and cell lines. Experimental up-regulation miR-29a-3p with mimic could inhibit cell proliferation, but induced cell cycle arrest at G0/G1 phase and apoptosis in CRC cells. MiR-29a-3p overexpression significantly down-regulated the expression levels of CDK4, Cyclin D1, and Bax, but up-regulated the expression levels of p21 and Bcl-2 in DLD-1 cells. Moreover, ribosomal protein S15A (RPS15A) was predicted and confirmed as a direct target gene of miR-29a-3p. Furthermore, restoration of RPS15A could rescue the phenotypic changes caused by miR-29a-3p. The findings demonstrate miR-29a-3p inhibits CRC cell function possibly by targeting RPS15A, which might be exploited therapeutically in CRC.
Cloning and identification of the Frigocyclinone biosynthetic gene cluster from Streptomyces griseus strain NTK 97
Authors: Mo Jian , Ye Jiang , Chen Haozhe , Hou Bingbing , Wu Haizhen , Zhang Huizhan 
Published: July 2019

ABSTRACT
Frigocyclinone is a novel antibiotic with antibacterial and anticancer activities. It is produced by both Antarctica-derived Streptomyces griseus NTK 97 and marine sponge-associated Streptomyces sp. M7_15. Here, we first report the biosynthetic gene cluster of frigocyclinone in the S. griseus NTK 97. The frigocyclinone gene cluster spans a DNA region of 33-kb which consists of 30 open reading frames (ORFs), encoding minimal type II polyketide synthase, aromatase and cyclase, redox tailoring enzymes, sugar biosynthesis-related enzymes, C-glycosyltransferase, a resistance protein, and three regulatory proteins. Based on the bioinformatic analysis, a biosynthetic pathway for frigocyclinone was proposed. Second, to verify the cloned gene cluster, CRISPR-Cpf1 mediated gene disruption was conducted. Mutant with the disruption of beta-ketoacyl synthase encoding gene frig20 fully loses the ability of producing frigocyclinone, while inactivating the glycosyltransferase gene frig1 leads to the production of key intermediate of anti-MRSA anthraquinone tetrangomycin.
Computing the self-consistent field in Kohn–Sham density functional theory
Authors: Woods N D , Payne M C , Hasnip P J 
Published: July 2019

Abstract
A new framework is presented for evaluating the performance of self-consistent field methods in Kohn–Sham density functional theory (DFT). The aims of this work are two-fold. First, we explore the properties of Kohn–Sham DFT as it pertains to the convergence of self-consistent field iterations. Sources of inefficiencies and instabilities are identified, and methods to mitigate these difficulties are discussed. Second, we introduce a framework to assess the relative utility of algorithms in the present context, comprising a representative benchmark suite of over fifty Kohn–Sham simulation inputs, the scf-x

n
suite. This provides a new tool to develop, evaluate and compare new algorithms in a fair, well-defined and transparent manner.
Determining dose enhancement factors of high-Z nanoparticles from simulations where lateral secondary particle disequilibrium exists
Authors: Rabus Hans , Gargioni Elisabetta , Li Wei Bo , Nettelbeck Heidi , Villagrasa Carmen 
Published: July 2019

Abstract
Nanoparticles (NPs) containing high atomic number (high-Z) materials have been shown to enhance the radiobiological effectiveness of ionizing radiation. This effect is often attributed to an enhancement of the absorbed dose in the vicinity of the NPs, based on Monte Carlo simulations that show a significant local enhancement of the energy deposition on the microscopic scale. The results of such simulations may be significantly biased and lead to a severe overestimation of the dose enhancement if the condition of secondary particle equilibrium is not met in the simulation setup. This current work shows an approach to estimate a ‘realistic’ dose enhancement from the results of such biased simulations which is based on published photon interaction data and provides a way for correcting biased results.
Mott polaritons in cavity-coupled quantum materials
Authors: Kiffner Martin , Coulthard Jonathan , Schlawin Frank , Ardavan Arzhang , Jaksch Dieter 
Published: July 2019

Abstract
We show that strong electron–electron interactions in quantum materials can give rise to electronic transitions that couple strongly to cavity fields, and collective enhancement of these interactions can result in ultrastrong effective coupling strengths. As a paradigmatic example we consider a Fermi–Hubbard model coupled to a single-mode cavity and find that resonant electron-cavity interactions result in the formation of a quasi-continuum of polariton branches. The vacuum Rabi splitting of the two outermost branches is collectively enhanced and scales with

g

eff

∝

2
L

, where L is the number of electronic sites, and the maximal achievable value for g
eff is determined by the volume of the unit cell of the crystal. We find that g
eff for existing quantum materials can by far exceed the width of the first excited Hubbard band. This effect can be experimentally observed via measurements of the optical conductivity and does not require ultrastrong coupling on the single-electron level. Quantum correlations in the electronic ground state as well as the microscopic nature of the light–matter interaction enhance the collective light–matter interaction compared to an ensemble of independent two-level atoms interacting with a cavity mode.
Fabrication and characterization of optical nanofiber interferometer and resonator for the visible range
Authors: Ding Chengjie , Loo Vivien , Pigeon Simon , Gautier Romain , Joos Maxime , Wu E , Giacobino Elisabeth , Bramati Alberto , Glorieux Quentin 
Published: July 2019

Abstract
We report the fabrication and characterization of photonic structures using tapered optical nanofibers. Thanks to the extension of the evanescent electromagnetic field outside of the nanofiber two types of devices can be built: a ring interferometer and a knot resonator. We propose a general approach to predict the properties of these structures using the linear coupling theory. In addition, we describe a new source of birefringence due to the ovalization of a nanofiber under strong bending, known in mechanical engineering as the Brazier effect.
Subradiance-protected excitation transport
Authors: Needham Jemma A , Lesanovsky Igor , Olmos Beatriz 
Published: July 2019

Abstract
We explore excitation transport within a one-dimensional chain of atoms where the atomic transition dipoles are coupled to the free radiation field. When the atoms are separated by distances smaller or comparable to the wavelength of the transition, the exchange of virtual photons leads to the transport of the excitation through the lattice. Even though this is a strongly dissipative system, we find that the transport is subradiant, that is, the excitation lifetime is orders of magnitude longer than the one of an individual atom. In particular, we show that a subspace of the spectrum is formed by subradiant states with a linear dispersion relation, which allows for the dispersionless transport of wave packets over long distances with virtually zero decay rate. Moreover, the group velocity and direction of the transport can be controlled via an external uniform magnetic field while preserving its subradiant character. The simplicity and versatility of this system, together with the robustness of subradiance against disorder, makes it relevant for a range of applications such as lossless energy transport and long-time light storage.
Machine learning by unitary tensor network of hierarchical tree structure
Authors: Liu Ding , Ran Shi-Ju , Wittek Peter , Peng Cheng , García Raul Blázquez , Su Gang , Lewenstein Maciej 
Published: July 2019

Abstract
The resemblance between the methods used in quantum-many body physics and in machine learning has drawn considerable attention. In particular, tensor networks (TNs) and deep learning architectures bear striking similarities to the extent that TNs can be used for machine learning. Previous results used one-dimensional TNs in image recognition, showing limited scalability and flexibilities. In this work, we train two-dimensional hierarchical TNs to solve image recognition problems, using a training algorithm derived from the multi-scale entanglement renormalization ansatz. This approach introduces mathematical connections among quantum many-body physics, quantum information theory, and machine learning. While keeping the TN unitary in the training phase, TN states are defined, which encode classes of images into quantum many-body states. We study the quantum features of the TN states, including quantum entanglement and fidelity. We find these quantities could be properties that characterize the image classes, as well as the machine learning tasks.
Trends and controls of terrestrial gross primary productivity of China during 2000–2016
Authors: Ma Jun , Xiao Xiangming , Miao Renhui , Li Yao , Chen Bangqian , Zhang Yao , Zhao Bin 
Published: July 2019

Abstract
Terrestrial gross primary productivity (GPP) is an important flux that drives the global carbon cycle. However, quantifying the trend and the control factor of GPP from the pixel level to the regional level is still a challenge. We generated monthly GPP dataset using the vegetation photosynthesis model and calculated the interannual linear trend for China during 2000–2016. The Breaks For Additive Seasonal and Trend method was applied to detect the timing of breakpoint and trends shift of monthly GPP, while boosted regression tree analysis was used to identify the most important factor and its relative influence on GPP based on gridded leaf area index (LAI), aerosol optical thickness, and NCEP-DOE Reanalysis II meteorological data. The results show that annual mean GPP was significantly (P < 0.001, R
2 = 0.78) increased, especially in the Loess Plateau and South China, from 2000 to 2016. The change rate of annual mean GPP declined from 18.82 g C m−2 yr−1 in 2000–2008 to 3.48 g C m−2 yr−1 in 2008–2016. About 55.4% of the breakpoints occur between 2009 and 2011 and was mainly distributed in Qinghai-Tibet Plateau, Central China, Southwestern China, and South China, and negative oriented GPP trends variation type still accounts for about 28.76%. LAI and temperature related factors generally had the highest relative influence on GPP in the north part and south part of China, respectively. Our study indicates that the ecological restoration projects and rapid urbanization have respectively induced the most obvious increase and decrease trends of GPP in China. Land cover change and climate change are the main reasons for GPP dynamics in the north and south part of China, respectively.
High harmonic generation with Laguerre–Gaussian beams
Authors: Paufler Willi , Böning Birger , Fritzsche Stephan 
Published: July 2019

Abstract
We summarize the development of high harmonic generation (HHG) with linearly polarized Laguerre–Gaussian (LG) beams and their superpositions to explain the non-perturbative aspects of HHG. Furthermore, we show that circularly polarized extreme ultraviolet vortices with well-defined orbital angular momentum (OAM) can be generated by HHG with bicircular LG beams. We introduce photon diagrams in order to explain how to calculate the OAM and the polarization of the generated harmonics by means of simultaneous conservation of spin angular momentum and OAM. Moreover, we show how the intensity ratio of the driving fields in HHG with bicircular LG beams further enhances the generation of circularly polarized twisted attosecond pulse trains.
Fabry–Perot type resonant modes of exciton luminescence in Cu2O nanowires
Authors: Wang Peng , Liu Guipeng , Zhao Xinhong , Li Hairong , Li Lingshan , Lian Junbo , Gao Xiaohu , Huang Zeyu 
Published: July 2019

Abstract
Single Cu2O nanowires (NWs) were fabricated by the two-step method we reported previously (Wang et al 2014 RSC Advances
4 37542). Band-edge exciton photoluminescence (PL) was observed from individual NWs at room temperature using excitation at 325 nm. The PL signals were assigned to Fabry–Perot (F-P) type standing waves in a right cylindrical dielectric cavity (resonator) for a representative range of different wire lengths and diameters. We found that the mode spacing of F-P resonances varied inversely as the NW length as expected. For the region of NW diameters from 140 to 200 nm, and NW length between 2–5 mm, E-field simulations by COMSOL Multiphysics finite element analysis indicate that the main F-P mode propagating inside the NW is the HE11 mode. When the diameter exceeds 200 nm, there are at least two F-P type modes supported in the NWs. Our results further the understanding of exciton photoluminescence in Cu2O NWs and demonstrates the existence of enhanced mode frequencies based on the geometry of the optical micro-cavity. We further identify potential applications in exciton-driven optoelectronic devices and light emission enhanced by optical micro-cavities.
Reconsidering Domesticity through the Lens of Empire and Settler Society in North America
Authors: Sklar Kathryn Kish 
Published: July 2019

Abstract
Our reconsideration of domesticity comes at a time when empire and colonial and postcolonial categories of analysis are informing many fields of historical study. This essay traces the historiographic origins of the intersection of domesticity and empire, focusing on domesticity’s usefulness as a window on cross-cultural intimacy and conflict. It also offers an example of how previous treatments of domesticity might be revised by taking empire and settler society into account.
Identifying emerging phenomenon in long temporal phenotyping experiments
Authors: Peng Jiajie , Lu Junya , Hoh Donghee , Dina Ayesha S , Shang Xuequn , Kramer David M , Chen Jin 
Published: July 2019

AbstractMotivationThe rapid improvement of phenotyping capability, accuracy and throughput have greatly increased the volume and diversity of phenomics data. A remaining challenge is an efficient way to identify phenotypic patterns to improve our understanding of the quantitative variation of complex phenotypes, and to attribute gene functions. To address this challenge, we developed a new algorithm to identify emerging phenomena from large-scale temporal plant phenotyping experiments. An emerging phenomenon is defined as a group of genotypes who exhibit a coherent phenotype pattern during a relatively short time. Emerging phenomena are highly transient and diverse, and are dependent in complex ways on both environmental conditions and development. Identifying emerging phenomena may help biologists to examine potential relationships among phenotypes and genotypes in a genetically diverse population and to associate such relationships with the change of environments or development.ResultsWe present an emerging phenomenon identification tool called Temporal Emerging Phenomenon Finder (TEP-Finder). Using large-scale longitudinal phenomics data as input, TEP-Finder first encodes the complicated phenotypic patterns into a dynamic phenotype network. Then, emerging phenomena in different temporal scales are identified from dynamic phenotype network using a maximal clique based approach. Meanwhile, a directed acyclic network of emerging phenomena is composed to model the relationships among the emerging phenomena. The experiment that compares TEP-Finder with two state-of-art algorithms shows that the emerging phenomena identified by TEP-Finder are more functionally specific, robust and biologically significant.Availability and implementationThe source code, manual and sample data of TEP-Finder are all available at: http://phenomics.uky.edu/TEP-Finder/.Supplementary informationSupplementary data are available at Bioinformatics online.