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BaTiO3 solid solutions co-doped with Gd3+ and Eu3+:Synthesis,structural evolution and dielectric properties

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Journal of rare Earths 2024年第10期42卷 1920-1926页

作者： r.Martínez-López M.Pérez-Labra J.A.romero-Serrano F.r.barrientos-Hernández M.reyes-Pérez M.I.Valenzuela-Carrillo G.Urbano-reyes V.E.reyes-Cruz G.I.Dávila-Pulido Academic Area of Earth Sciences and Materials Autonomous University of Hidalgo State Metallurgy and Materials Department ESIQIE-IPNUPALM Autonomous University of Coahuila Boulevard Adolfo López Mateos S/n

In this paper,the synthesis,structural evolution,and dielectric properties of BaTiO3solid solutions codoped with rare earth elements(Gd3+and Eu3+) prepared using the solid-state reaction method are *** pure precursor powders of BaCl3,TiO2,Gd2O3,and Eu2O3were mixed in stoichiometric proportions,ground in an agate mortar before being uniaxially pressed at 250 MPa and sintered at 1300℃ in air atmosphere for 6 h to obtain Ba1-3xGd2xTi1-3xEu4xO3（x=0,0.0015,0.01 and0.1）.X-ray diffraction（XrD） and rietveld's refinement results reveal the crystal phase ferroelectric tetragonal BaTiO3for the samples with x=0,0.0015 and 0.01, as well as a consistent increment in the lattice parameters caused by the *** solubility limit of Gd3+and Eu3+in the BaTiO3structure is reached for the sample with x>0.01,and the orthorhombic Eu2TiO5and monoclinic BaTi2O5secondary phases were *** raman results show the characteristic peaks of ferroelectric tetragonal BaTiO3around 716 cm-1（LO of A1 symmetry）,515 cm-1（TO of A1 symmetry）,and 305 cm-1（B1）.The maximum relative permittivity measured at 1 kHz was recorded to be 6151.8 for the sample with x=0.0015,and a decrease in the Curie temperature to 105℃ with respect to the undoped sample was *** punctual microanalysis for the samples with x=0.0015,0.01,and 0.1 reveals grains composed of Ba,Ti,O,Gd,and Eu homogeneously distributed in the *** Ba/Ti ratios for samples with x=0.0015,0.01 and 0.1 are 2.86,2.91,and 0.68,respectively,indicating substitution at the Ti site for samples with x=0.0015 and 0.01 and a substitution at the Ba site for the sample with x=0.1.

关键词： BaTiO3 Doping Europium Gadolinium rare earths Synthesis

Dependence of Upper Atmosphere Photochemistry on the Shape of the Diurnal Cycle of the Photolysis rates

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Advances in Atmospheric Sciences 2006年第2期23卷 207-214页

作者： Sonia MONTECINOS Patricia barrientos Center of Advanced Studies in Arid Zones (CEAZA) University of La Serena La SerenaChile Department of Physics University of La Frontera TemucoChile

A photochemical model of the atmosphere constitutes a non-linear, non-autonomous dynamical system, enforced by the Earth＇s rotation. Some studies have shown that the region of the mesopause tends towards non-linear responses such as period-doubling cascades and chaos. In these studies, simple approximations for the diurnal variations of the photolysis rates are assumed. The goal of this article is to investigate what happens if the more realistic, calculated photolysis rates are introduced. It is found that, if the usual approximations-sinusoidal and step fiunctions—are assumed, the responses of the system axe similar： it converges to a 2-day periodic solution. If the more realistic, calculated diurnal cycle is introduced, a new 4-day subharmonic appear.

关键词： photochemical models bifurcation theory numerical solutions dynamical systems

Policy Iteration Algorithms for Zero-Sum Stochastic Differential Games with Long-run Average Payoff Criteria

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Journal of the Operations research Society of China 2014年第4期2卷 395-421页

作者： JoséDaniel López-barrientos Faculty of Actuarial Sciences Universidad Ana´huacMe´xico NorteHuixquilucanMexico

This paper studies the policy iteration algorithm(PIA)for zero-sum stochastic differential games with the basic long-run average criterion,as well as with its more selective version,the so-called bias *** system is assumed to be a nondegenerate *** use Lyapunov-like stability conditions that ensure the existence and boundedness of the solution to certain Poisson *** also ensure the convergence of a sequence of such solutions,of the corresponding sequence of policies,and,ultimately,of the PIA.

关键词： Ergodic payoff criterion Zero-sum stochastic differential games Policy iteration algorithm Nondegenerate diffusions Poisson equation Schäl convergence Bias game

Crop adaptation to climate change:An evolutionary perspective

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Molecular Plant 2023年第10期16卷 1518-1546页

作者： Lexuan Gao Michael B.Kantar Dylan Moxley Daniel Ortiz-barrientos Loren H.rieseberg CAS Center for Excellence in Molecular Plant Sciences Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghai 200032China Department of Tropical Plant&Soil Sciences University of Hawaii at ManoaHonoluluHIUSA Department of Botany and Biodiversity research Centre University of British ColumbiaVancouverBCCanada School of Biological Sciences and Australian research Council Centre of Excellence for Plant Success in Nature and Agriculture The University of QueenslandBrisbaneQLDAustralia

The disciplines of evolutionary biology and plant and animal breeding have been intertwined throughout their development,with responses to artificial selection yielding insights into the action of natural selection and evolutionary biology providing statistical and conceptual guidance for modern *** we offer an evolutionary perspective on a grand challenge of the 21st century:feeding humanity in the face of climate *** first highlight promising strategies currently under way to adapt crops to current and future climate *** include methods to match crop varieties with current and predicted environments and to optimize breeding goals,management practices,and crop microbiomes to enhance yield and sustainable *** also describe the promise of crop wild relatives and recent technological innovations such as speed breeding,genomic selection,and genome editing for improving environmental resilience of existing crop varieties or for developing new ***,we discuss how methods and theory from evolutionary biology can enhance these existing strategies and suggest novel *** focus initially on methods for reconstructing the evolutionary history of crops and their pests and symbionts,because such historical information provides an overall framework for crop-improvement *** then describe how evolutionary approaches can be used to detect and mitigate the accumulation of deleterious mutations in crop genomes,identify alleles and mutations that underlie adaptation(and maladaptation)to agricultural environments,mitigate evolutionary trade-offs,and improve critical *** feedback between the evolution and crop biology communities will ensure optimal design of strategies for adapting crops to climate change.

关键词： abiotic stress resistance climate change crop adaptation Darwinian agriculture evolutionary biology plant breeding

Exploiting Deep Learning Techniques for Colon Polyp Segmentation

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Computers, Materials & Continua 2021年第5期67卷 1629-1644页

作者： Daniel Sierra-Sosa Sebastian Patino-barrientos Begonya Garcia-Zapirain Cristian Castillo-Oleam Adel Elmaghraby Department of Computer Science and Engineering University of LouisvilleLouisvilleKYUSA Centro de Computacion Cientifica Apolo at Universidad EAFIT MedelinColombia eVida research Group University of DeustoBilbaoSpain

As colon cancer is among the top causes of death, there is a growinginterest in developing improved techniques for the early detection of colonpolyps. Given the close relation between colon polyps and colon cancer,their detection helps avoid cancer cases. The increment in the availability ofcolorectal screening tests and the number of colonoscopies have increasedthe burden on the medical personnel. In this article, the application of deeplearning techniques for the detection and segmentation of colon polyps incolonoscopies is presented. Four techniques were implemented and evaluated:Mask-rCNN, PANet, Cascade r-CNN and Hybrid Task Cascade (HTC).These were trained and tested using CVC-Colon database, ETIS-LArIBPolyp, and a proprietary dataset. Three experiments were conducted to assessthe techniques performance: (1) Training and testing using each databaseindependently, (2) Mergingd the databases and testing on each database independently using a merged test set, and (3) Training on each dataset and testingon the merged test set. In our experiments, PANet architecture has the bestperformance in Polyp detection, and HTC was the most accurate to segmentthem. This approach allows us to employ Deep Learning techniques to assisthealthcare professionals in the medical diagnosis for colon cancer. It is anticipated that this approach can be part of a framework for a semi-automatedpolyp detection in colonoscopies.

关键词： Colon polyps deep learning image segmentation

Atacama Field Campaign: laboratory and in-situ measurements for remote sensing applications

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International Journal of Digital Earth 2019年第1期12卷 43-61页

作者： Cristian Mattar Andrés Santamaría-Artigas Flavio Ponzoni Cibele T.Pinto Carolina barrientos Glynn Hulley Laboratory for Analysis of the Biosphere(LAB) University of ChileSantiagoChile Department of Geographical Sciences University of MarylandCollege ParkMDUSA Divisão de Sensoriamento remoto(DSr) Instituto Nacional de Pesquisas Espaciais(INPE)São PauloBrasil Aerial Photogrammetric Service(SAF) Chilean Air ForceSantiagoChile Jet Propulsion Laboratory(JPL) California Institute of TechnologyPasadenaCAUSA

This work presents the preliminary results of the first field calibration campaign performed in the Atacama Desert,Chile,between the 18 and 22 August 2014,called the Atacama Field Campaign(ATAFIC 2014).In situ measurements were performed in order to spectrally characterize the surface reflectance spectra between 0.3 and 2.5μm,radiometric temperature(8.0–14.0μm)and atmospheric measurements.A soil sample was collected and analyzed using Fourier Transform Infrared Spectroscopy and X-ray Diffraction techniques to characterize the surface reflectance spectra and mineralogical composition,*** land surface emissivity in addition to GOES,MODIS and Landsat-8 land surface temperature(LST)were also *** showed that the spectral features of the Atacama soil and the characteristics of this geographical zone,which is featured as the most hyper-arid and cloudless place in the world,make this area a potential target for surface reflectance *** and night LST comparison between field and remote sensing data are lower than 2 K and the root Mean Square Error for land surface emissivity is close to 2%.This work opens the possibilities to consider the Atacama Desert as a reference target for calibration and validation activities for earth observation missions’purposes.

关键词： Atacama spectroradiometry emissivity temperature surface reflectance

Lower marine productivity increases agonistic interactions between sea lions and fur seals in Northern Pacific Patagonia

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Current Zoology 2022年第6期68卷 657-666页

作者： Felipe MONTALVA Hector PAVES Diego PErEZ-VENEGAS Karin G barrientos E Carola VALENCIA Diego MIrANDA-UrBINA Mauricio SEGUEL Facultad de Ciencias Biologicas Pontificia Universidad Catolica de ChileSantiagoChile Departamento de Ciencias Basicas Facultad de CienciasUniversidad Santo TomasOsornoChile Centro de Investigacion y Gestion de recursos Naturales(CIGrEN) Instituto de BiologıaFacultad de CienciasUniversidad de ValparaısoValparaısoChile Programa de Doctorado en Ciencias Agrarias Escuela de Graduados de laFacultad de Ciencias Agrarias y AlimentariasUniversidad Austral de ChileValdiviaChile Facultad de Medicina Veterinaria Sede PatagoniaUniversidad San SebastianPuerto MonttChile Instituto de Ciencias Biologicas Universidad de TalcaTalcaChile Department of Pathobiology Ontario Veterinary CollegeUniversity of GuelphGuelphCanada

Interspecific interactions are key drivers of individual and population-level fitness in a wide range of ***,in marine ecosystems,it is relatively unknown which biotic and abiotic factors impact behavioral interactions between competing *** assessed the impact of weather,marine productivity,and population structure on the behavioral agonistic interactions between South American fur seals(SAFSs),Arctocephalus australis,and South American sea lions(SASLs),Otaria byronia,in a breeding colony of *** hypothesized that agonistic interactions between SAFSs and SASLs respond to biotic and abiotic factors such as SAFS population structure,marine productivity,and *** found that SASL and SAFS interactions almost always resulted in negative impacts on the social structure or reproductive success of the SAFS *** adult males initiated stampedes of SAFS and/or abducted and predated SAFS *** SAFS males abundance and severe weather events were negatively correlated with agonistic interactions between ***,proxies for lower marine productivity such as higher sea surface temperature and lower catches of demerso-pelagic fish were the most important predictors of more frequent agonistic interactions between SAFS and *** the current scenario of decline in marine biomass due to global climate change and overfishing,agonistic interactions between competing marine predators could increase and exacerbate the negative impacts of environmental change in these species.

关键词： interspecific interactions climate change Guafo Island sea surface temperature South American fur seal South American sea lion

Numerical Simulations of Nonlinear Interaction of Space Charge Waves in Microwave and Millimeter Wave range in n-InN Films Using Negative Differential Conductivity

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Modeling and Numerical Simulation of Material Science 2014年第3期4卷 136-142页

作者： Abel Garcia-barrientos Volodymyr Grimalsky CIICAp Autonomous University of Morelos State (UAEM) Morelos México Electronics and Computer Science Department Research Center on Information Technology and Systems Autonomous University of Hidalgo State (UAEH) Hidalgo México

Numerical simulations of nonlinear interaction of space charge waves in microwave and millimeter wave range in n-InN films have been carried out. A micro- and millimeter-waves frequency conversion using the negative differential conductivity phenomenon is carried out when the harmonics of the input signal are generated. An increment in the amplification is observed in n-InN films at essentially at high-frequencies f red with n-GaAs films f rk provides a way to achieve a frequency conversion and amplification of micro- and millimeter-waves.

关键词： Space Charge Waves InN Film Negative Differential Conductivity

Insulin sensitizers in treatment of nonalcoholic fatty liver disease:Systematic review

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World Journal of Gastroenterology 2006年第48期12卷 7826-7831页

作者： Norberto C Chavez-Tapia Tonatiuh barrientos-Gutierrez Felix I Tellez-ávila Francisco Sánchez-ávila Maria Antonieta Montao-reyes Misael Uribe Department of Gastroenterology Instituto Nacional de Ciencias Médicas y Nutrición Zalvador Zubirán Mexico City Mexico The University of Texas School of Public Health Houston United States Instituto de Educación Media Superior Mexico City Mexico

AIM: To summarize the evidence available for the clinical effectiveness of insulin sensitizers in the treatment of nonalcoholic fatty liver disease (NAFLD) systematically. METHODS: relevant articles were located using computer-assisted searches of Medline (1966-March 2006), EMBASE (1988-March 2006), CINAHL (1982-March 2003), Educational resource Information Center (1966-March 2006), Library, Information Science & Technology Abstracts (1967-March 2006), Cochrane Database of Systematic reviews, Database of Abstracts of reviews of Effects (1994-2006), dissertations in ProQuest and FirstSearch databases. Manual searches were made in the abstracts from meetings of the American Gastroenterological Association (1999-2006), and the American Association for the Study of Liver Diseases (2003-2005). Studies were retrieved using the following selection criteria: (1) clinical trials using insulin sensitizers in subjects with NAFLD, (2) adult patients, (3) published as full manuscripts or abstracts, and (4) English, Spanish, German, and French languages only. Data were abstracted independently by two reviewers following standardized procedures. A face-to- face comparison of data was conducted to ensure the completeness and reliability of the abstraction process. rESULTS: Nine studies were included, six using metformin and three using thiazolidinediones. Only two studies were placebo-controlled trials. The mediansample size for all studies was 18 subjects. In the placebo-controlled trials, metformin improved insulin resistance markers and liver function tests, but not histological scores. In the single-arm trials, metformin and thiazolidinediones improved insulin resistance markers and liver function tests, and beneficial histological changes were reported. There is limited high-quality information available from which to draw categorical conclusions about the clinical use of insulin sensitizers in ***: Current information indicates that the use of insulin sensitizers

关键词： Steatohepatitis Evidence based medicine Systematic review