bluuebunny/crossref_metadata_2025_split huggingface dataset:
A soft switching four‐phase converter with ultra‐high step down conversion ratio and automatic uniform current sharing
Authors: Asghari Amin 
Published: April 2021

AbstractThis paper introduces a new high step down four‐phase converter with soft switching and automatic uniform current sharing. The phase number of the introduced topology can be expanded. In this converter, the main switches are turned on under zero voltage zero current switching condition and turned off under zero voltage switching. Also, the auxiliary switches and diodes operate respectively under zero voltage switching and zero current switching conditions. In the proposed architecture, the duty cycle is extended and the semiconductors voltage stress is reduced by applying series capacitors and coupled inductors. The leakage energy associated with the coupled inductors is absorbed and the reverse recovery losses of diodes are eliminated. Uniform current sharing between four phases is achieved without any extra current sharing control circuit. Furthermore, by utilizing the interleaved method, the current stress and the output current ripple are reduced. This converter provides above advantages while its input and output grounds are connected. As a result, the introduced topology can provide high step down conversions at high frequencies. The converter operation and its characteristics are analysed in detail. The accuracy of the theoretical analysis is verified by a laboratory prototype.
A new characteristic peaks group judgement method for the accurate measurement of time‐of‐flight in the ultrasonic gas flowmeter
Authors: Zheng Dandan , Mao Yang , Yang Zhibin 
Published: April 2021

AbstractAs a typical method for calculating time‐of‐flight (TOF), the double‐threshold method is widely applied in many time‐difference‐based ultrasonic gas flowmeters. However, the cycle‐skip phenomenon caused by noises and various flowrate often affects the accuracy and reliability of flowmeters. Based on traditional double‐threshold method and other improved double‐threshold methods, a new characteristic peaks group judgement method is proposed for calculating TOF in this work. In this method, the peak's characteristics of the received signal are used to find the feature point which is stable in different flowrates. Then, based on the feature point, zero‐crossing detection is executed for calculating TOF. In order to evaluate the new method, it is compared with traditional double‐threshold method and the similarity judgment‐based double‐threshold method through offline tests on both simulated signals and real‐flow signals. Results show that the proposed method can effectively eliminate the cycle‐skip phenomenon and has higher precision and reliability than other methods. Furthermore, a digital signal‐processing‐based ultrasonic gas flowmeter with this method was implemented. Three calibration experiments were carried out on a gas flow standard device. The calibration results show that the flowmeter can achieve accuracy of class 1 in a wide velocity range from 1 to 35 m/s.
Effects of noise and time delay on E2F's expression level in a bistable Rb‐E2F gene’s regulatory network
Authors: Kirunda John Billy , Yang Lijian , Lu Lulu , Jia Ya 
Published: April 2021

AbstractThe bistable Rb‐E2F gene regulatory network plays a central role in regulating cellular proliferation‐quiescence transition. Based on Gillespie's chemical Langevin method, the stochastic bistable Rb‐E2F gene’s regulatory network with time delays is proposed. It is found that under the moderate intensity of internal noise, delay in the Cyclin E synthesis rate can greatly increase the average concentration value of E2F. When the delay is considered in both E2F‐related positive feedback loops, within a specific range of delay (3‐13), the average expression of E2F is significantly increased. Also, this range is in the scope with that experimentally given by Dong et al. [65]. By analysing the quasi‐potential curves at different delay times, simulation results show that delay regulates the dynamic behaviour of the system in the following way: small delay stabilises the bistable system; the medium delay is conducive to a high steady‐state, making the system fluctuate near the high steady‐state; large delay induces approximately periodic transitions between high and low steady‐state. Therefore, by regulating noise and time delay, the cell itself can control the expression level of E2F to respond to different situations. These findings may provide an explanation of some experimental result intricacies related to the cell cycle.
Influence of dry run speed on the cleaning of compressor blade
Authors: Tang Jie , Gao Dianrong , Wang Liwen , Zeng Jie 
Published: April 2021

AbstractTo optimize the on‐line cleaning process parameters of aero‐engines, the influence of the engine's dry run Speed on the cleaning flow field was analysed. Through the reverse modelling and numerical simulation of the CFM56‐7B compressor, the changes of static pressure, velocity and vorticity of the cleaning flow field under different dry run speeds were analysed. The results showed that the static pressure and speed of the cleaning flow field increased linearly with the increase of the dry run speed; the vortex of the cleaning flow field decreases with the increase of the speed, but the increase of the speed was beneficial to the cleaning of the compressor. Through the aero‐engines online cleaning test, comparing the recovery of EGTM at different speeds, when the engine dry run speed was 323 r/min, a better cleaning effect and higher economic benefits can be obtained. The research can provide a theory for engine online cleaning.
Carrier frequency offsets problem in recent DST‐SC‐FDMA system: Investigation and compensation
Authors: Al‐kamali Faisal S. , Al‐Soufy Khaled A. 
Published: April 2021

AbstractCarrier frequency offset (CFO) is a challenging problem in the uplink of the single‐carrier frequency division multiple access (SC‐FDMA) system. CFOs effect on the orthogonality between subcarriers and cause inter‐carrier interference (ICI) and multiple access interference (MAI). This paper, analyzes the impact of the CFOs on the performance of the Discrete Sine Transform (DST) SC‐FDMA (DST‐SC‐FDMA) system and investigates with different wireless channels, different modulation schemes and different subcarriers mapping schemes. Furthermore, an efficient equalization and CFOs compensation scheme is proposed to enhance the performance of the DST‐ SC‐FDMA system and transmit images efficiently over DST‐ SC‐FDMA system. The proposed scheme combines the minimum mean square error (MMSE) equalizer and the parallel interference cancellation (PIC). The combined method is referred to as MMSE+PIC. The results show that CFOs degrades the DST‐FDMA performance. The obtained results show a noticeable performance improvement of the proposed MMSE‐PIC scheme over the conventional MMSE equalizer. Moreover, it is found that it is possible to efficiently transmit wireless image using the proposed MMSE+PIC scheme,
Clustered star formation toward Berkeley 87/ON2
Authors: de la Fuente Diego , Román-Zúñiga Carlos G. , Jiménez-Bailón Elena , Alves João , Garcia Miriam , Venus Sean 
Published: April 2021

Context. Disentangling line-of-sight alignments of young stellar populations is crucial for observational studies of star-forming complexes. This task is particularly problematic in a Cygnus-X subregion where several components, located at different distances, overlap: the Berkeley 87 young massive cluster, the poorly known [DB2001] Cl05 embedded cluster, and the ON2 star-forming complex, which in turn is composed of several H II regions.
Aims. We provide a methodology for building an exhaustive census of young objects that can consistently treat large differences in extinction and distance.
Methods. OMEGA2000 near-infrared observations of the Berkeley 87/ON2 field were merged with archival data from Gaia, Chandra, Spitzer, and Herschel and with cross-identifications from the literature. To address the incompleteness effects and selection biases that arise from the line-of-sight overlap, we adapted existing methods for extinction estimation and young object classification. We also defined the intrinsic reddening index, Rint, a new tool for separating intrinsically red sources from those whose infrared color excess is caused by extinction. Finally, we introduce a new method for finding young stellar objects based on Rint.
Results. We find 571 objects whose classification is related to recent or ongoing star formation. Together with other point sources with individual estimates of distance or extinction, we compile a catalog of 3005 objects to be used for further membership work. A new distance for Berkeley 87, (1673 ± 17) pc, is estimated as a median of 13 spectroscopic members with accurate Gaia EDR3 parallaxes.
Conclusions. The flexibility of our approach, especially regarding the Rint definition, allows overcoming photometric biases caused by large variations in extinction and distance in order to obtain homogeneous catalogs of young sources. The multiwavelength census that results from applying our methods to the Berkeley 87/ON2 field will serve as a basis for disentangling the overlapped populations.
Advantages of a curved image plate for rapid laboratory-based x-ray total scattering measurements: Application to pair distribution function analysis
Authors: Irving Daniel J. M. , Keen David A. , Light Mark E. 
Published: April 2021

The analysis and interpretation of the pair distribution function (PDF), as derived from total scattering measurements, is still seen by many as a technique confined to central synchrotron and neutron facilities. This situation has begun to change with a rising visibility of total scattering experiments reported in mainstream scientific journals and the modification of an increasing number of laboratory diffractometers. However, the rigor required during data reduction and the complexities of data interpretation mean the technique is still very far from being routine. Herein, we report the first application of a large area curved image plate system based on a Rigaku SPIDER (R-AXIS RAPID II) equipped with an Ag tube for collecting data amenable to high quality PDF refinement/modeling of crystalline, amorphous, and liquid samples. The advantages of such a system are the large Q range available without scanning (routinely in excess of 20 Å−1) and the inherent properties of an image plate detector (single photon sensitivity, large dynamic range [1.05 × 106], and effectively zero noise). Data are collected and structural models refined for a number of standard materials including NIST 640f silicon for which a Rwp ≤ 0.12 value was obtained with data collected in 60 min (excluding background measurements). These and other data are discussed and compared to similar examples in the literature.
Radial profile measurement with an improved 1 kHz Thomson scattering system on Versatile Experiment Spherical Torus
Authors: Kim Jung-Hwa , Kim Young-Gi , Kim Doyeon , Lee Jong-ha , Hwang Y. S. 
Published: April 2021

A Thomson scattering (TS) system has been utilized to measure the electron temperature and density of the core region of Versatile Experiment Spherical Torus (VEST). Recently, the laser injection system is successfully upgraded adopting the burst laser with the repetition rate of 1 kHz and the energy of 2 J. Furthermore, improved collection optics with additional polychromators and a 32-channel fast digitizer are prepared to observe the fast time evolution of radial profiles. This improvement is essential to study fast phenomena such as internal reconnection event (IRE). We increase the TS signal and reduce the stray light by introducing new filters having better optical properties such as high optical density at 1064 nm, transmission, and reflectance. Moreover, the optimum reverse bias voltages are newly set to make the system operational independent of the background radiation. As a result, 1 kHz radial profiles of the core electron temperature and density are measured for the first time, showing characteristics of IREs in VEST.
Fast skeletal myosin-binding protein-C regulates fast skeletal muscle contraction
Authors: Song Taejeong , McNamara James W. , Ma Weikang , Landim-Vieira Maicon , Lee Kyoung Hwan , Martin Lisa A. , Heiny Judith A. , Lorenz John N. , Craig Roger , Pinto Jose Renato , Irving Thomas , Sadayappan Sakthivel 
Published: April 2021

Significance
Myosin-binding protein-C (MyBP-C) is a thick filament regulatory protein found exclusively in the C-zone of the A-band in the sarcomeres of vertebrate striated muscle. Cardiac, slow skeletal, and fast skeletal MyBP-C (fMyBP-C) paralogs perform different functions. All three paralogs share similar protein structures but likely differ substantially in terms of expression and function, which may serve the distinct physiologies of fast and slow muscle fibers. However, the functional role of fMyBP-C in fast skeletal muscle is completely unknown. Genetic mutations in human fMyBP-C lead to skeletal myopathies. In this study, we used knockout mice to define the molecular basis for fMyBP-C paralog diversity. We demonstrate that fMyBP-C modulates the speed and force of fast skeletal muscle contraction.
Circulating mitochondrialN-formyl peptides contribute to secondary nosocomial infection in patients with septic shock
Authors: Kwon Woon Yong , Suh Gil Joon , Jung Yoon Sun , Park Seung Min , Oh Subi , Kim Sung Hee , Lee A. Rum , Kim Jeong Yeon , Kim Hayoung , Kim Kyung Ah , Kim Young , Kim Byoung Choul , Kim Taegyun , Kim Kyung Su , Itagaki Kiyoshi , Hauser Carl J. 
Published: April 2021

SignificanceSeptic shock commonly leads to multiorgan injury both directly via tissue inflammation and secondarily via hypoperfusion, but both can result in mitochondrialN-formyl peptide (mtFP) release into the circulation. However, no studies have evaluated the role of circulating mtFPs during septic shock. We found that a relatively high plasma nicotinamide adenine dinucleotide dehydrogenase subunit-6 (the most potent human mtFP) level was independently associated with the development of secondary infection in patients with septic shock and that the increased susceptibility to secondary infection is partly attributed to the suppression of polymorphonuclear leukocyte (PMN) chemotaxis by mtFP occupancy of formyl peptide receptor-1. Incorporation of these findings into therapeutic strategies may improve clinical outcomes in septic shock patients by preventing PMN chemotactic anergy.
Viral packaging ATPases utilize a glutamate switch to couple ATPase activity and DNA translocation
Authors: Pajak Joshua , Atz Rockney , Hilbert Brendan J. , Morais Marc C. , Kelch Brian A. , Jardine Paul J. , Arya Gaurav 
Published: April 2021

Significance
Many biological processes are performed by ring-shaped molecular motors that harvest energy from ATP hydrolysis to move DNA, RNA, or protein substrate through their central pores. However, it is not clear how these proteins couple their physical movement to the chemical steps of ATP hydrolysis. Here, we derive the molecular mechanism by which viral DNA packaging motors couple ATP binding to DNA gripping and ATP hydrolysis to DNA release. We first predict the coupling pathway computationally with molecular dynamics simulations and then validate our predictions experimentally with structural and functional measurements. The mechanism derived and presented here could be broadly applicable to all ring ATPase motors.
Achatina fulica (giant African land snail).
Authors: Vogler Roberto E , Beltramino Ariel A 
Published: April 2021

Abstract

The giant African land snail A. fulica is a fast-growing polyphagous plant pest that has been introduced from its native range in East Africa to many parts of the world as a commercial food source (for humans, fish and livestock) and as a novelty pet. It easily becomes attached to any means of transport or machinery at any developmental stage, is able to go into a state of aestivation in cooler conditions and so is readily transportable over distances. Once escaped it has managed to establish itself and reproduce prodigiously in tropical and some temperate locations. As a result, A. fulica has been classified as one of the world's top 100 invasive alien species by The World Conservation Union, IUCN (ISSG, 2003).
ICOS signaling limits regulatory T cell accumulation and function in visceral adipose tissue
Authors: Mittelsteadt Kristen L. , Hayes Erika T. , Campbell Daniel J. 
Published: April 2021

A unique population of Foxp3+ regulatory T cells (TRs) resides in visceral adipose tissue (VAT) that regulates adipose inflammation and helps preserve insulin sensitivity. Inducible T cell co-stimulator (ICOS) is highly expressed on effector (e)TRs that migrate to nonlymphoid tissues, and contributes to their maintenance and function in models of autoimmunity. In this study, we report an unexpected cell-intrinsic role for ICOS expression and downstream phosphoinositide 3-kinase (PI3K) signaling in limiting the abundance, VAT-associated phenotype, and function of TRs specifically in VAT. Icos−/− mice and mice expressing a knock-in form of ICOS that cannot activate PI3K had increased VAT-TR abundance and elevated expression of canonical VAT-TR markers. Loss of ICOS signaling facilitated enhanced accumulation of TRs to VAT associated with elevated CCR3 expression, and resulted in reduced adipose inflammation and heightened insulin sensitivity in the context of a high-fat diet. Thus, we have uncovered a new and surprising molecular pathway that regulates VAT-TR accumulation and function.
Graviton backreaction on the local cosmological expansion in slow-roll inflation
Authors: Lima William C C 
Published: April 2021

Abstract
We compute the graviton one-loop correction to the expectation value of the local expansion rate in slow-roll inflation, with both slow-roll parameters finite. The calculation is based on a recent method to explicitly construct gauge-invariant observables in perturbative quantum gravity at all orders in perturbation theory, and it is particularly suited in cases of highly-symmetrical space-time backgrounds. Our analysis adds to recent calculations of that correction in de Sitter space-time and in single-field inflation with constant deceleration. In the former case a vanishing one-loop correction was found, while in the latter the quantum backreaction produces a secular effect that accelerates the expansion. The quantum correction we describe here produces a finite secular effect that can either accelerated or decelerate the background expansion, depending on the value of the slow-roll parameters.
Graded magnetic materials
Authors: Fallarino Lorenzo , Kirby Brian J , Fullerton Eric E 
Published: April 2021

Abstract
Graded magnetic materials represent a promising new avenue in modern material science from both fundamental and application points of view. Over the course of the last few years, remarkable results have been obtained in (epitaxial) heterostructures based on thin alloy films featuring diverse compositional depth profiles. As a result of the precise tailoring of such profiles, the exchange coupling, and the corresponding effective or local Curie temperatures can be controlled over tens of nm with an excellent precision. This topical review article reports the most recent advances in this emerging research field. Several aspects are covered, but the primary focus lies in the study of compositional gradients being transferred into depth dependent magnetic states in ferromagnets, while also reviewing other experimental attempts to create exchange graded films and materials in general. We account for the remarkable progress achieved in each sample and composition geometry by reporting the recent developments and by discussing the research highlights obtained by several groups. Finally, we conclude the review article with an outlook on future challenges in this field.
Development of detailed pediatric eye models for lens dose calculations
Authors: Han Haegin , Yeom Yeon Soo , Nguyen Thang Tat , Choi Chansoo , Shin Bangho , Moon Sungho , Ha Sangseok , Son Gahee , Augusteyn Robert , Kim Chan Hyeong 
Published: April 2021

Abstract
The International Commission on Radiological Protection (ICRP) recently reduced the dose limit for the eye lens for occupational exposure from 150 mSv yr−1 to 20 mSv yr−1, as averaged over defined periods of five years, with no annual dose in a single year exceeding 50 mSv, emphasizing the importance of the accurate estimation of lens dose. In the present study, for more accurate lens dosimetry, detailed eye models were developed for children and adolescents (newborns and 1, 5, 10, and 15 year olds), which were then incorporated into the pediatric mesh-type reference computational phantoms (MRCPs) and used to calculate lens dose coefficients (DCs) for photon and electron exposures. Finally, the calculated values were compared with those calculated with the adult MRCPs in order to determine the age dependence of the lens DCs. For photon exposures, the lens DCs of the pediatric MRCPs showed some sizable differences from those of the adult MRCPs at very low energies (10 and 15 keV), but the differences were all less than 35%, except for the posterior-anterior irradiation geometry, for which the lens dose is not of primary concern. For electron exposures, much larger differences were found. For the anterior-posterior (AP) and isotropic irradiation geometries, the largest differences between the lens DCs of the pediatric and adult phantoms were found in the energy range of 0.6–1 MeV, where the newborn lens DCs were larger by up to a factor of ∼5 than the adult. The lens DCs of the present study, which were calculated for the radiosensitive region of the lens, also were compared with those for the entire lens in the AP irradiation geometry. Our results showed that the DCs of the entire lens were similar to those of the radiosensitive region for 0.02–2 MeV photons and >2 MeV electrons, but that for the other energy ranges, significant differences were noticeable, i.e. 10%–40% for photons and up to a factor of ∼5 for electrons.
On the uncertainty of boundary-layer parameters from Ensemble PTV data
Authors: Castellanos R , Sanmiguel Vila C , Güemes A , Discetti S 
Published: April 2021

Abstract
The recent advancements in high-resolution turbulence-statistics computation from ensemble particle tracking velocimetry (EPTV) data are now opening new possibilities in turbulent-flow characterisation. Measurements of full-field boundary layer profiles with a fine resolution close to the wall and up to the freestream with one single imaging setup are now feasible, thus paving the way to direct characterisation of turbulent-boundary-layer (TBL) parameters with composite-profile formulations. In this work, we build a framework for the estimation of the uncertainty of EPTV in performing this task. The effect of systematic errors due to finite spatial resolution and of random error due to convergence are investigated under different window size. Then we introduce random errors to simulate the effects on convergence issues on the velocity profile and, consequently, on the estimation of turbulent-boundary-layer parameters. The statistical dispersion of the estimated parameters provides an estimation of the uncertainty range. We validate with experimental data this flexible tool to estimate a priori the expected uncertainty level of the most relevant turbulent-boundary-layer parameters in zero-pressure-gradient TBL, being the method based on existing profiles from high-fidelity simulation or from analytical composite-profile formulations when such data are not available.