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Heterogeneities of grain boundary contact for simulation of laboratoryscale mechanical behavior of granitic rocks

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第7期16卷 2629-2644页

作者： Xiongyu Hu Marte gutierrez Zhiwei Yan Key Laboratory of Transportation Tunnel Engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu610031China University Transportation Center for Underground Transportation Infrastructure Colorado School of MinesGoldenUSA School of Civil Engineering Southwest Jiaotong UniversityChengdu610031China

From a practical point of view,grain structure heterogeneities are key parameters that control the rock response and still remains a challenge to incorporate in a quantitative *** of the less discussed topics in the context of the grain-based model(GBM)in the particle flow code(PFC)is the contact heterogeneities and the appropriate contact model to mimic the grain boundary ***,the smooth joint(SJ)model and linear parallel bond(LPB)model are used to simulate the grain boundary ***,the literature does not document the suitability of different models for specific *** challenge in implementing GBM in PFC is that only a single bonding parameter is used at the grain *** aim of this study is to investigate the responses of a laboratory-scale specimen with SJ and LPB models,considering grain boundary heterogeneous and homogeneous contact *** and biaxial compression tests are performed to calibrate the response of Creighton *** stressestrain curves,volumetric dilation,inter-crack(crack in the grain boundary),and intra-crack(crack within the grain)development,and failure patterns associated with different contact models are *** was found that both the SJ and LPB models can reproduce the pre-peak behavior observed for a granitic rock ***,the LPB model is unable to reproduce the post-peak *** to the large interlocking effect originating from the balls in contact and the ball size in the LPB model,local dilation is induced at the grain *** overestimates the volumetric dilation and residual shear *** LPB model tends to result in discontinuous inter-cracks and stress localization in the rock specimen,resulting in fine fragments at the rock surface during failure.

关键词： Grain boundary contact Smooth joint(SJ)model Linear parallel bond(LPB)model Contact heterogeneities Particle flow code(PFC) Granitic rock

Predicting the coefficient of friction in a sliding contact by applying machine learning to acoustic emission data

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Friction 2024年第6期12卷 1299-1321页

作者： Robert gutierrez Tianshi FANG Robert MAINWARING Tom REDDYHOFF Tribology Group Department of Mechanical EngineeringImperial College LondonExhibition RoadLondon SW72AZUK Shell Global Solutions(US)Inc.Shell Technology Center Houston 3333 Highway 6 SouthHoustonTX 77082USA Shell International Petroleum Company Limited Shell CentreYork RoadLondon SE17NAUK

It is increasingly important to monitor sliding interfaces within machines,since this is where both energy is lost,and failures *** emission(AE)techniques offer a way to monitor contacts remotely without requiring transparent or electrically conductive ***,acoustic data from sliding contacts is notoriously complex and difficult to ***,we simultaneously measure coefficient of friction(with a conventional force transducer)and acoustic emission(with a piezoelectric sensor and high acquisition rate digitizer)produced by a steel‒steel rubbing *** data is then used to train machine learning(ML)algorithms(e.g.,Gaussian process regression(GPR)and support vector machine(SVM))to correlated acoustic emission with *** training requires the dense AE data to first be reduced in size and a range of processing techniques are assessed for this(e.g.,down-sampling,averaging,fast Fourier transforms(FFTs),histograms).Next,fresh,unseen AE data is given to the trained model and the resulting friction predictions are compared with the directly measured *** is excellent agreement between the measured and predicted friction when the GPR model is used on AE histogram data,with root mean square(RMS)errors as low as 0.03 and Pearson correlation coefficients reaching ***,predictions remain accurate despite changes in test conditions such as normal load,reciprocating frequency,and stroke *** paves the way for remote,acoustic measurements of friction in inaccessible locations within machinery to increase mechanical efficiency and avoid costly failure/needless maintenance.

关键词： acoustic emission condition monitoring friction machine learning Gaussian process regression support vector machine

Grazing Pressure and Plant Functional Types in Puna Highlands,Northwestern Argentina

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Phyton-International Journal of Experimental Botany 2024年第5期93卷 1067-1080页

作者： Quiroga Mendiola mariana Tálamo Andrés IPAF NOA—INTA(National Institute for Agricultural Technology) Posta de HornillosJujuy4622Argentina Facultad de Ciencias Naturales Universidad Nacional de SaltaSalta4400Argentina Instituto de Bio y Geociencias del NOA(IBIGEO) UNSa-CONICET.Laboratorio de Ecología Aplicada a la Conservación(LEAC)Facultad de Ciencias NaturalesUniversidad Nacional de SaltaSalta4400Argentina Maestría en Gestión Ambiental Escuela de NegociosUniversidad Católica de Salta(UCASAL)Salta4400Argentina

The Puna grasslands support grazing systems that produce meat and wool in multi-species herds,especially from llama(Lama glama)and ***,it is yet unknown whether grazing pressure can modify grassland structure and Plant Functional Types diversity and cover in Puna *** analyzed the relationship between grazing pressure and Plant Functional Types by comparing transects located near stockyards(high grazing pressure)and far from them(low pressure)and by evaluating the relationship between the Plant Functional Types cover to a Grazing Pressure Index(GPI).This index incorporates the heterogeneity of traditional pastoral *** two ecological sites(Ciénego and Tolar),we sampled paired transects(near-far).Plots near and far from corrals were similar in all the variables measured except for plots in Tolar,which tend to have higher total cover,possibly due to fecal fertilization near ***,we recorded an increase in total cover and grass cover at higher GPI in Ciénego,while in Tolar we found lower values of total cover and herbaceous dicotyledonous cover at intermediate intensities of *** only negative relationship found was the cover of clonal and non-clonal shrubs,possibly explained by the greater use of these shrubs as firewood near *** summary,our study does not show important changes in Plant Functional Types as a function of grazing pressure in the studied grasslands probably because grazing pressure is diluted or diminished when livestock rotates in different areas and grazing durations ***,the long grazing history with which the Puna has evolved could also contribute to the co-structuration between native vegetation and livestock farming.

关键词： Natural grasslands Puna herbivory ecological perturbation

Representation of three-dimensional mass distribution of the Earth's interior by biorthogonal series and its use for studying internal structure of the planet

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Geodesy and Geodynamics 2024年第3期15卷 264-275页

作者： Mykhailo Fys mariana Yurkiv Andrii Brydun Andrii Sohor Department of Cartography and Geospatial Modelling Lviv Polytechnic National UniversityLviv 79013Ukraine

This paper utilizes the mathematical concept of approximation within an ellipsoid from a single viewpoint to present the spatial mass distribution function of the Earth's interior and its internal *** primary focus lies in constructing the volume distribution of masses in the planet's interior, with the expansion coefficients being linear combinations of the Stokes constants. Several possible approaches are suggested for determining accurately these coefficients employing three-dimensional(biorthogonal)polynomials. By expressing the mass distribution function of the Earth's interior and its internal potential as a series, an algorithm is introduced for the calculation of gravitational energy. It allows us to estimate fluctuations in gravitational energy. The implementation of this algorithm offers the means of establishing the extent to which the Earth deviates from a state of hydrostatic equilibrium as a celestial *** to the aforementioned method, calculations have been conducted to validate its effectiveness and reliability. This example is given as an illustration of a given method for studying the internal structure of planets.

关键词： Mass distribution function Potential Stokes constants Biorthogonal polynomials

Annual variation of adult survival of a south-temperate House Wren population in Argentina

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Avian Research 2024年第2期15卷 229-237页

作者： Gustavo J.Fernandez mariana E.Carro Paulo E.Llambías Grupo de Investigacion en Ecofisiología de Fauna Silvestre INIBIOMA-CONICETAsentamiento Universitario San Martín de los Andes(AUSMA)Universidad Nacional Del ComahuePasaje de la Paz 235(8370)San Martín de los AndesNeuquenArgentina Grupo de Investigacion de Biología de Aves IADIZA CCT-MendozaUniversidad Nacional de CuyoAvenida RuizLeal s/n Parque General San Martin5500MendozaArgentina

Identifying factors affecting the survival of individuals is essential for understanding the evolution of life-history traits and population *** numerous studies on this subject in north-temperate environments,there is a lack of equivalent studies at similar latitudes in the ***,we used a 14-year dataset of capture,banding,and resighting to estimate the annual variation in the apparent adult survival probability of a south-temperate population of House Wrens(Troglodytes aedon bonariae).We evaluated temporal variation in sur-vival and the effect of environmental(climatic)and demographic variables(adult abundance,total number of fledglings produced during each breeding season)on survival *** found that the probability of adult survival decreased as the abundance of breeding adults *** density-dependent effect could be related to the resident lifestyle of southern House Wrens,which could determine an intense competition for territories and resources that ultimately would affect their survival.

关键词： Annual variation CJS Density-dependence Survival Troglodytes aedon bonariae

From prediction to prevention:Machine learning revolutionizes hepatocellular carcinoma recurrence monitoring

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World Journal of Gastroenterology 2024年第7期30卷 631-635页

作者： mariana Michelle Ramírez-Mejía Nahum Méndez-Sánchez Plan of Combined Studies in Medicine Faculty of MedicineNational Autonomous University of MexicoDistrito Federal 04510Mexico Liver Research Unit Medica Sur Clinic&FoundationDistrito Federal 14050Mexico Faculty of Medicine National Autonomous University of MexicoDistrito Federal 04510Mexico

In this editorial,we comment on the article by Zhang et al entitled Development of a machine learning-based model for predicting the risk of early postoperative recurrence of hepatocellular *** carcinoma(HCC),which is characterized by high incidence and mortality rates,remains a major global health challenge primarily due to the critical issue of postoperative *** recurrence,defined as recurrence that occurs within 2 years posttreatment,is linked to the hidden spread of the primary tumor and significantly impacts patient *** predictive factors,including both patient-and treatment-related factors,have limited predictive ability with respect to HCC *** integration of machine learning algorithms is fueled by the exponential growth of computational power and has revolutionized HCC *** study by Zhang et al demonstrated the use of a groundbreaking preoperative prediction model for early postoperative HCC *** persist,including sample size constraints,issues with handling data,and the need for further validation and *** study emphasizes the need for collaborative efforts,multicenter studies and comparative analyses to validate and refine the *** these challenges and exploring innovative approaches,such as multi-omics integration,will enhance personalized oncology *** study marks a significant stride toward precise,efficient,and personalized oncology practices,thus offering hope for improved patient outcomes in the field of HCC treatment.

关键词： Hepatocellular carcinoma Early recurrence Machine learning XGBoost model Predictive precision medicine Clinical utility Personalized interventions

Alzheimer’s visual variant: a report of a diagnosis easily missed on ophthalmic examination

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International Journal of Ophthalmology(English edition) 2024年第8期17卷 1571-1575页

作者： Jorge Cárdenas-Belaunzarán Lorena Wheelock-gutierrez Karen ACerrillo-Avila Department of Neuro-Ophthalmology Association to Prevent Blindness in MexicoI.A.P.Mexico City 04030Mexico Independent Researcher Mexico City 04040Mexico

Dear Editor,We present a case of posterior cortical atrophy(PCA),which is a syndromic entity caused by different neurodegenerative diseases,mainly Alzheimer’s disease,but it has been described in several other *** frequency is reported to be as high as 5%of all cases;however,it remains widely under-recognized among ophthalmologists and optometrists due to scarce reports in visual health-related journals[1].

关键词： diagnosis Alzheimer diseases

Complications Associated with Autologous Fat Transfer: Case Report and Literature Review

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Modern Plastic Surgery 2024年第1期14卷 1-8页

作者： Bryan Armando Morales eslava Carlos Emiliano García Cordova Antoine Arturo Lagunes Gasca Department of Surgery Hospital Regional Petróleos Mexicanos Villahermosa Tabasco Mexico Department of Surgery Hospital Central Sur Petróleos Mexicanos Mexico City Mexico

Undoubtedly, since its appearance, the interest and use of autologous fat transfer (AFT) as a breast reconstruction technique have been increasing, becoming one of the main surgical alternatives for aesthetic breast augmentation. This increase in its popularity has led to the development of new technologies to increase its efficacy and safety, however, it has inherently implied the inadequate use of this procedure, mainly when performed by unqualified medical personnel. We present the case of a patient with complications following a breast AFT for aesthetic purposes, performed by a general practitioner without a specialty in plastic and reconstructive surgery.

关键词： Breast Breast Reconstruction Breast Surgery Autologous Fat Transfer Intramammary Abscess

Changes in call properties of Boana pulchella (Anura, Hylidae) in response to different noise conditions

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Current Zoology 2024年第4期70卷 548-556页

作者： Pablo Grenat Maria Ferrero mariana Baraquet Favio Pollo Manuel Otero Zulma Salinas Nancy Salas Adolfo Martino Ecologia Departamento de Ciencias NaturalesFacultad de Ciencias ExactasFisico-Quimicas y NaturalesUniversidad Nacional de Rio CuartoRutaNacional N°36-km601X5804BYARioCuartoArgentina lnstituto de Ciencias de la Tierra Biodiversidad y Ambiente(ICBIA)UNRC-CONICETRuta Nacional N°36-km 601X5804BYARio CuartoArgentina Cátedra de Botanica General Departamento de Recursos Naturales y AmbienteFacultad de AgronomiaUniversidad de Buenos AiresAv.San Martin 4453Buenos AiresArgentina

The increasing expansion of urban areas leads to the emergence of new noisy environments that can affect animal *** play a crucial role in the mating displays of anurans,and the negative impact of anthropogenic noise-induced auditory masking has been reported in several *** investigated the acoustic variation in 96 males(n=971 calls)of the treefrog Boana pulchella across acoustically undis-turbed sites and different noise conditions,associated with urban areas(URBAN)and roads(ROAD),in Central *** analyzed the effect of anthropogenic noise conditions on 6 temporal(call duration[CD],intercall interval,first and second note duration,internote interval,and call rate)and 3 spectral(dominant frequency of first and second note,frequency difference between them)call *** effects of temperature and size on acoustical variables were *** observed differences in all call attributes among the noise conditions,except for intercall *** exposed to URBAN and ROAD exhibited significant changes in CD,dominant frequency of the second note,and fre-quency difference between *** males had longest internote interval,while ROAD individuals displayed increased first and second note duration and call ***,ROAD males exhibited immediate changes in call rate in direct response to passing heavy *** study emphasizes the impact of anthropogenic noise on the acoustic characteristics of *** *** how animals adapt to noisy environments is crucial in mitigating the adverse effects of urbanization on their communication *** investigations should explore whether the observed call adjustments are effective in avoiding or mitigating the negative consequences of anthropogenic noise on reproductive success.

关键词： acoustic communication advertisement call auditory masking noise pollution road traffic noise.