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Investigation of radio pulsar emission features using power spectra

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Research in Astronomy and Astrophysics 2018年第8期18卷 63-70页

作者： Valery M.Malofeev sergey A.Tyul'bashev EN.Lebedev Physical Institute of the Russian Academy of Sciences V.V.Vitkevich Pushchino Radio Astronomy ObservatoryPRAO ASC FIANPushchinoRussia

Since 2013, round-the-clock monitoring of the sky has been carried out simultaneously in 96 beams using a high-sensitivity radio telescope called the Large Phased Array （LPA） at the frequency 110.25 MHz. These observations are made under the program of interplanetary plasma investigation. The same data are used to search for pulsars by means of power spectra. To increase the sensitivity of the pulsar search, 500-600 power spectra corresponding to different days of observations are summed. In the integrated spectra of known pulsars, besides expected improvement in signal-to-noise （S/N） ratio for the frequency harmonics, some features are explored in this paper. We present the 27 strongest pulsars which are in a field with declination 21° - 42°. The observable details in the integrated power spectra are connected with the presence of pulsar periods of the second （P2） and third （P3） class, which have been identified. Empirical relations for calculating these periods are obtained. The value P2 is estimated for 26 pulsars, and for 15 sources it is made for the first time. The value P3 is estimated for 13 pulsars, among them these values are given for five sources for the first time.

关键词： pulsars general - pulsars

K^+ retention in leaf mesophyll, an overlooked component of salinity tolerance mechanism:A case study for barley

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Journal of Integrative Plant Biology 2015年第2期57卷 171-185页

作者： Honghong Wu Min Zhu Lana Shabala Meixue Zhou sergey Shabala School of Land and Food University of Tasmania

Plant salinity tolerance is a physiologically complex trait, with numerous mechanisms contributing to it. In this work, we show that the ability of leaf mesophyll to retain K＋ represents an important and essentially overlooked component of a salinity tolerance mechanism. The strong positive correlation between mesophyll K＋ retention ability under saline conditions （quantified by the magnitude of NaCl-induced K＋ efflux from mesophyll） and the overall salinity tolerance （relative fresh weight and/or survival or damage under salinity stress） was found while screening 46 barley （Hordeum vulgare L.） genotypes contrasting in their salinity tolerance. Genotypes with intrinsically higher leaf K＋ content under control conditions were found to possess better K＋ retention ability under salinity and, hence, overall higher tolerance. Contrary to previous reports for barley roots, K＋ retention in mesophyll was not associated with an increased H＋-pumping in tolerant varieties but instead correlated negatively with this trait. These findings are explained by the fact that increased H＋ extrusion may be needed to charge balance the activity and provide the driving force for the high affinity HAK/KUP K＋ transporters required to restore cytosolic K＋ homeostasis in salt-sensitive genotypes.

关键词： Cytosolic K+ homeostasis ion flux membrane potential membrane transport tissue tolerance

Dynamic magnetic hysteresis in a liquid suspension of acicular maghemite particles

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Particuology 2009年第6期7卷 451-458页

作者： Bronislav E.Kashevsky sergey B.Kashevsky Igor V.Prokhorov A.V.Luikov Heat and Mass Transfer Institute Belarus Academy of SciencesP.Brovka str.15Minsk 220072Belarus

This paper presents theoretical and experimental studies on the magnetodynamics and energy absorption in a dilute suspension of small ferromagnetic particles with magnetic hysteresis and mechanical mobility in an AC magnetic field. Experiments with 0.1% suspensions of acicular particles of gamma ferric oxide in solid and liquid matrices, subjected to a 430 Hz magnetic field with an intensity of up to 1200 Oe, revealed important role of particle mobility. The main qualitative and quantitative features of the phenomenon are in agreement with a model of joint magneto-mechanical dynamics of particles with a chain-of-spheres mode of incoherent magnetic reversal.

关键词： High-coercive magnetic particles Magnetic suspensions Dynamic magnetic hysteresis

Variations in defect substructure and fracture surface of commercially pure aluminum under creep in weak magnetic field

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Chinese Physics B 2017年第12期26卷 427-431页

作者： sergey Konovalov Dmitry Zagulyaev 陈希章 Victor Gromov Yurii Ivanov Samara National Research University Samara 443086 Russia Wenzhou University Wenzhou 325035 China Siberian State Industrial University Novokuznetsk 654007 Russia Institute of High Current Electronics of the Siberian Branch of the Russia Academy of Sciences Tomsk 634055 Russia

Commercially pure polycrystalline aluminum of grade A85, as a test material, is investigated. Using scanning and transmission electron microscopy the aluminum fine structure and fracture surface are analyzed. Fractures are studied in the regime of creep with and without a simultaneous effect of 0.3-T magnetic field. It is found that the application of a magnetic field in a linear stage of creep leads to substructure imperfection increasing. Furthermore, the magnetic field effect on aluminum in the process of creep causes the average scalar density of dislocations to increase and induces the process of dislocation loop formation to strengthen. Fractographic investigation of the fracture surface shows that in the fibrous fracture zone the average size of plastic fracture pits decreases more than twice under creep in the condition of external magnetic field compared with in the conventional experimental condition. In a shear zone, the magnetic field causes the average size of fracture pits to decrease. Experimental data obtained in the research allow us to conclude that the magnetic field effect on aluminum in the process of creep leads to the fracture toughness value of the material decreasing, which will affect the state of defect substructure of the volume and surface layer of the material. The influence of the magnetic field is analyzed on the basis of the magneto-plasticity effect.

关键词： aluminum magnetic field creep structure

Assessing suspended sediment fluxes with acoustic Doppler current profilers:case study from large rivers in Russia

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Big Earth Data 2022年第4期6卷 504-526页

作者： sergey Chalov Vsevolod Moreido Victor Ivanov Aleksandra Chalova Faculty of Geography Lomonosov Moscow State UniversityMoscowRussia Institute of Physics Kazan Federal UniversityKazanRussia Flood Hydrology Lab Water Problems Institute of Russian Academy of SciencesMoscowRussia

Surrogate measures are becoming increasingly used to measure suspended sediment flux,but only few particular computer techniques of data processing are recently *** study demonstrates capabilities of acoustic Doppler current profilers(ADCPs)to infer information regarding suspended-sand concentrations in river systems and calculate suspended sediment flux via big data analytics which includes process of analyzing and data mining of measurements based on ADCP signal backscatter intensity *** present here specific codes done by R language using RStudio software with open-source tidyverse and plotly packages aimed to generate tables containing data of suspended load for cells,verticals and whole cross-section based on backscattering values from 600 kH Teledyne RDInstruments RioGrande WorkHorse ADCP unit,as well perform estimates of morphometric,suspended sediment concentration(SSC)and velocity characteristics of the *** developed tools enabled to process large data array consisting of over 56,526,480 geo-referenced values of river depth,streamflow velocity,and backscatter intensity for each river cross-section measured at six case study sites in Russia.

关键词： Big data ADCP backscatter intensity sediment transport

Domain wall-localized phonons in BiFeO_(3):spectrum and selection rules

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npj Computational Materials 2020年第1期6卷 1255-1260页

作者： Peng Chen Louis Ponet Keji Lai Roberto Cingolani sergey Artyukhin Quantum Materials Theory Istituto Italiano di Tecnologia16163 GenovaItaly Scuola Normale Superiore di Pisa 56126 PisaItaly Department of Physics University of Texas at AustinAustinTX 78712USA

Ferroelectric domain walls(DWs)are nanoscale topological defects that can be easily tailored to create nanoscale *** excitations,recently discovered to be responsible for GHz DW conductivity,hold promise for faster signal transmission and processing compared to the existing *** we find that DW phonons have unprecedented dispersion going from GHz all the way to THz frequencies,and resulting in a surprisingly broad GHz signature in DW *** activation of nominally forbidden DW sliding modes in BiFeO_(3) is traced back to DW tilting and resulting asymmetry in wall-localized *** obtained phonon spectra and selection rules are used to simulate scanning impedance microscopy,emerging as a powerful probe in *** results will guide the experimental discovery of the predicted phonon branches and design of DWbased nanodevices operating in the technologically important frequency range.

关键词： phonon walls faster

Solvent induced enhancement of nonlinear optical response of graphdiyne

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Chinese Chemical Letters 2021年第1期32卷 525-528页

作者： Yuze Dong sergey Semin Yaqing Feng Jialiang Xu Theo Rasing School of Chemical Engineering and Technology Tianjin UniversityTianjin 300350China Radboud University Institute for Molecules and Materials(IMM)Heyendaalseweg 1356525AJNijmegenthe Netherlands School of Materials Science and Engineering Nankai UniversityTianjin 300350China Collaborative Innovation Center of Chemical Science and Engineering(Tianjin) Tianjin UniversityTianjin 300072China

Flat and crystalline materials with exceptional nonlinear optical(NLO) properties are highly desirable for their potential applications in integrated NLO photonic ***(GD),a new twodimensional(2 D) carbon allotrope,has recently evoked burgeoning research attention by virtue of its tunable bandgap along with a high carrier mobility and extended π-conjugation compared with most conventional optical ***,we experimentally probe the third-order nonlinear optical response of GD dispersed in several common solvents(alcohols) using a femtosecond Z-scan *** measured nonlinear optical refractive index is in the order of ~10^(-8) cm^(2)/W,which is approximately one order of magnitude higher than that of most 2 D *** particular,we find that different NLO responses can be observed from GD when dispersed in different solvents,with the strongest NLO response when dispersed in *** is proposed that some intrinsic properties of the solvents,such as the polarity and viscosity,could influence the NLO response of GD *** experimental results confirm the assumptions on the NLO behavior in GD and demonstrate its great potential for future generations of Kerr-effect-based NLO materials and devices.

关键词： 2D materials Graphdiyne Nonlinear optics Kerr-effect Solvent effect

Trends in oxycodone and oxycodone-containing analgesics administration for back pain in emergency departments in the USA(2007–2018)

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World Journal of Emergency Medicine 2024年第3期15卷 169-174页

作者： Jonathan Chabon Jemer Garrido Deanna Schreiber-Gregory Jefferson Drapkin sergey Motov Department of Emergency Medicine Maimonides Medical CenterBrooklyn 11219USA

BACKGROUND:To describe trends in oxycodone and oxycodone-containing analgesic prescribing for the treatment of back pain among adults in emergency departments(EDs) in the USA from 2007 to ***:Data were gathered from the National Hospital Ambulatory Medical Care Survey(NHAMCS) from 2007 to *** study population included individuals of all ages presenting to USA *** NHAMCS reasons for visit and oxycodone drug ID codes were used to isolate patients with back *** main outcome was the proportion of oxycodone and oxycodone-containing analgesics prescribed for back pain in the EDs over the specified time ***:There was a relative decrease in the overall administration of oxycodone for back pain in the EDs by 62.3% from 2007(244,000 visits) to 2018(92,000 visits).The proportion of ED patients prescribed with oxycodone-containing analgesics for back pain increased among patients aged 45 years and older(from 43.8% to 57.6%),female patients(from 54.5% to 62.0%),black patients(from 22.5% to 30.4%),and Hispanic/Latino patients(from 9.4% to 19.6%).Oxycodone/acetaminophen was most prescribed and accounted for 90.2% of all oxycodone-containing analgesics in 2007,with a decrease to 68.5% in *** oxycodone was the second most prescribed medication,accounting for 6.1% in 2007 and 31.5% in ***:The overall number of oxycodone-containing analgesics decreased significantly from 2007 to ***,that number trended upward in 45-year-old and older,female,black,or Hispanic/Latino patients from 2007 to *** total amount of pure oxycodone increased significantly from 2007 to 2008.

关键词： Oxycodone Back pain Emergency department

Target acquisition performance in the presence of JPEG image compression

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Defence Technology（防务技术） 2024年第3期33卷 30-41页

作者： Boban Bondzulic Nenad Stojanovic Vladimir Lukin sergey A.Stankevich Dimitrije Bujakovic Sergii Kryvenko University of Defence in Belgrade Military AcademyVeljka Lukica Kurjaka 3311000 BelgradeSerbia National Aerospace University Department of Information-Communication TechnologiesChkalova 1761070 KharkivUkraine National Academy of Sciences of Ukraine Scientific Centre for Aerospace Research of the EarthOles Honchar 55-b01054 KyivUkraine

This paper presents an investigation on the effect of JPEG compression on the similarity between the target image and the background,where the similarity is further used to determine the degree of clutter in the *** new clutter metrics based on image quality assessment are introduced,among which the Haar wavelet-based perceptual similarity index,known as HaarPSI,provides the best target acquisition prediction *** is shown that the similarity between the target and the background at the boundary between visually lossless and visually lossy compression does not change significantly compared to the case when an uncompressed image is *** future work,through subjective tests,it is necessary to check whether this presence of compression at the threshold of just noticeable differences will affect the human target acquisition *** values are compared with the results of subjective tests of the well-known target Search_2 database,where the degree of agreement between objective and subjective scores,measured through linear correlation,reached a value of 90%.

关键词： JPEG compression Target acquisition performance Image quality assessment Just noticeable difference Probability of target detection Target mean searching time