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Gold grade variation and stream sediment geochemistry of the Vaimba-Lidi drainage system, northern Cameroon (West Africa)

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Natural Science 2013年第2期5卷 282-290页

作者： victor f. Embui Benjamin O. Omang Vivian B. Che Melvin T. Nforba Emmanuel C. Suh Department of Earth Sciences University of Yaounde I Yaounde Cameroon Department of Mineral Resource Engineering Technology Federal Polytechnic Auchi Auchi Nigeria Economic Geology Unit Department of Geology University of Buea Buea Cameroon Remote Sensing Unit Department of Geology University of Buea Buea Cameroon

Stream sediment geochemistry remains a versatile tool in exploration especially in regions where knowledge of the primary mineralization is lacking and the exploration activities are still at reconnaissance stage. In this study, we investigate the concentrations of gold and associated elements in stream sediment samples from the Vaimba-Lidi drainage system in northern Cameroon;a relatively remote area where alluvial gold is worked locally, and exploration activities are at early stage. The main river and its principal first and second order tributaries were sampled, panned for gold grain recovery and the 100 μm size fraction analyzed for Au by fire assay with Ni finish. A suite of other elements were analyzed for by inductively coupled plasma mass spectrometry (ICP-MS). Gold grades estimated by the panning and weighing technique rarely exceed1 g/t while the Au concentrations from chemical analysis range from 3.0 to 354.0 ppm. The spatial distribution of gold and all the other elements are presented as point symbol maps and the data analyzed using multivariate statistics. from the principal component analysis (PCA), the As-Mo-W-Ag as well as the Au-Zn factors point to the presence of primary hydrothermal gold-sulphide mineralization in the area and this can be further investigated. These results highlight the importance of multielement analysis and multivariate statistical interpretation of sediment geochemical data in inferring the nature of the underlying primary mineralization in any region.

关键词： Gold Grade Principal Component Analysis (PCA) Geochemistry Stream Sediments Cameroon

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A new friedelane triterpenoid and saponin with moderate antimicrobial activity from the stems of Drypetes laciniata

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Chinese Chemical Letters 2011年第2期22卷 171-174页

作者： Simone Veronique fannang victor Kuete Celine Mbazoa Djama Marlise Diane J.Dongfack Jean Duplex Wansi francois Tillequin Elisabeth Seguin Elizabeth Chosson Jean Wandji Laboratoire de Synthese et de Produits Naturels Departement de Chimie Organique de l'Universite de Yaounde-1Faculte des SciencesP.O.Box 812 YaoundeCameroon Department of Biochemistry University of DschangFaculty of ScienceP.O.Box 67 DschangCameroon Laboratoire de Pharmacognosie de l'Universite Paris Descartes UMR/CNRS No.8638Faculte des Sciences Biologiques et Pharmaceutiques4-Avenue de l'Observatoire75006 ParisFrance Department of Chemistry University of DoualaFaculty of ScienceP.O.Box 24157 DoualaCameroon Laboratoire de Pharmacognosie UFR de Medecine Pharmacie Rouen22-Bld Gambetta76183 Rouen Cedex 1France

A new friedelane-type triterpene named 3β-hydroxyfriedelane-7,12,22-trione,as well as nine known compounds were isolated from the whole stems of Drypetes laciniata Hutch.（Euphorbiaceae）.Their structures were established on the basis of spectroscopic *** new triterpene derivative and a known saponin were tested for antimicrobial and antifungal activities and they appeared to be moderate active.

关键词： Drypetes laciniata Euphorbiaceae Stem friedelane-type triterpenoid Antimicrobial activity

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The impact of poverty on dog ownership and access to canine rabies vaccination:results from a knowledge,attitudes and practices survey,Uganda 2013

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Infectious Diseases of Poverty 2017年第1期6卷 859-880页

作者： Ryan MacLaren Wallace Jason Mehal Yoshinori Nakazawa Sergio Recuenco Barnabas Bakamutumaho Modupe Osinubi victor Tugumizemu Jesse D.Blanton Amy Gilbert Joseph Wamala United States Centers for Disease Control and Prevention AtlantaGAUSA Uganda Virus Research Institute KampalaUganda Veterinary Public Health Division Ministry of HealthKampalaUganda World Health Organization KampalaUganda

Background:Rabies is a neglected disease despite being responsible for more human deaths than any other zoonosis.A lack of adequate human and dog surveillance,resulting in low prioritization,is often blamed for this *** methods are often employed to describe the rabies burden when surveillance data are not available,however these figures are rarely based on country-specific ***:In 2013 a knowledge,attitudes,and practices survey was conducted in Uganda to understand dog population,rabies vaccination,and human rabies risk factors and improve in-country and regional rabies burden *** and multi-level logistic regression techniques were conducted to estimate the total dog population and vaccination ***:Twenty-four villages were selected,of which 798 households completed the survey,representing 4375 *** owning households represented 12.9%of the population,for which 175 dogs were owned(25 people per dog).A history of vaccination was reported in 55.6%of owned *** and human population density highly correlated with dog ownership,and when accounted for in multi-level regression models,the human to dog ratio fell to 47:1 and the estimated national canine-rabies vaccination coverage fell to 36.1%.This study estimates there are 729486 owned dogs in Uganda(95%CI:719919-739053).Ten percent of survey respondents provided care to dogs they did not own,however unowned dog populations were not enumerated in this estimate.89.8%of Uganda’s human population was estimated to reside in a community that can support enzootic canine rabies ***:This study is the first to comprehensively evaluate the effect of poverty on dog ownership in *** results indicate that describing a dog population may not be as simple as applying a human:dog ratio,and factors such as poverty are likely to heavily influence dog ownership and vaccination *** modelled estimates should be confirmed through further f

关键词： Rabies Dogs Vaccination Poverty Low-income Neglected Africa

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Continuous wafer-scale graphene on cubic-SiC（O01）

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Nano Research 2013年第8期6卷 562-570页

作者： Alexander N. Chaika Olga V. Molodtsova Alexei A. Zakharov Dmitry Marchenko Jaime Sanchez-Barrig Andrei Varykhalov Igor V. Shvets victor Yu. Aristov Institute of Solid State Physics RAS Chemogolovka Moscow District 142432 Russia Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN) School of Physics Trinity College Dublin 2 Ireland HASYLAB at DESY D-22607 Hamburg Germany MAX-lab Lund University Box 118 22100 Lund Sweden Helmholtz-Zentrum Berlin für Materialien und Energie D- 12489 Berlin Germany

The atomic and electronic structure of graphene synthesized on commercially available cubic-SiC（001）/Si（001） wafers have been studied by low energy electron microscopy （LEEM）, scanning tunneling microscopy （STM）, low energy electron diffraction （LEED）, and angle resolved photoelectron spectroscopy （ARPES）. LEEM and STM data prove the wafer-scale continuity and uniform thickness of the graphene overlayer on SIC（001）. LEEM, STM and ARPES studies reveal that the graphene overlayer on SIC（001） consists of only a few monolayers with physical properties of quasi-freestanding graphene. Atomically resolved STM and micro-LEED data show that the top graphene layer consists of nanometer-sized domains with four different lattice orientations connected through the 〈110〉-directed boundaries. ARPES studies reveal the typical electron spectrum of graphene with the Dirac points close to the fermi level. Thus, the use of technologically relevant SiC（001）/Si（001） wafers for graphene fabrication repre-sents a realistic way of bridging the gap between the outstanding properties of graphene and their applications.

关键词： graphene cubic-SiC(001) STM ARPES LEEM LEED

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水平轴风力机合成射流流动控制数值研究

水平轴风力机合成射流流动控制数值研究

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作者： Olawoore victor Samuel 哈尔滨工业大学

学位级别：硕士

随着水平轴风力机(HAWT)尺寸的增加,在湍流大气边界层中运行时,流动分离效应造成的气动损失会更加显著地降低其性能和寿命,导致能源生产成本增加。合成射流作动器(SJAs)作为一种主动流动控制方法,与其他控制方法相比,具有响应速度快、... 详细信息

随着水平轴风力机(HAWT)尺寸的增加,在湍流大气边界层中运行时,流动分离效应造成的气动损失会更加显著地降低其性能和寿命,导致能源生产成本增加。合成射流作动器(SJAs)作为一种主动流动控制方法,与其他控制方法相比,具有响应速度快、功率要求低、几何复杂性低等特点,在航空航天应用中得到了广泛的研究,然而SJAs对水平轴风力机的驱动作用尚未得到充分的研究。本论文旨在对SJA特性进行数值研究,将其发展为一种有潜力的商用风力机主动流动控制方法(以额定工况下的NREL-5MW标准风力机为例研究)。NREL-5MW水平轴风力机为三叶型,半径63米,轮毂高度90米。这个涡轮机的额定功率是5兆瓦,进风风速为3 m/s,出风风速为25 m/s。为了降低计算成本,采用了周期性假设,只对其中一个叶片进行建模,计算网格采用ICEM软件进行划分,使用商用计算流体动力学ANSYS软件包对旋转参考系的雷诺平均Navier Stokes(RANS)方程进行求解。稳态分析采用SST k-ω湍流模型进行,因为该模型具有数值稳定性,并且能够在不利压力梯度的流动中表现良好,适用于本文所研究的工况。通过监测平均转矩结果、连续性和x、y、z动量方程,监测其仿真的收敛性,并依据已有数据进行验证。本文所得结论如下:(1)从空气动力学角度出发对NREL-5MW风力涡轮机进行了全面调查,指出尽管在叶梢分离效果降低,流动在叶根严重分离或停滞大规模回流由于当地增加攻角,这导致叶片在额定条件下的空气动力性能较差。(2)通过对无任何控制形式的全尺寸涡轮转子的数值模拟,指出叶片根部的流动分离效应会沿叶跨径向扩展,影响整个叶片的气动特性。(3)通过2.5D数值模拟,研究了流动分离对涡轮截面气动性能的影响。此外,还对基于合成射流作动器(SJA)的叶根分离流动控制进行了进一步的研究。使用了以下参数:射流角度为20度,无量纲频率f=0.8,射流动量系数C=1.5×10-3,基线升力系数提高了178%,阻力系数降低了18%。综上所述,叶根现象对气动性能的影响比目前文献中认为的要严重得多,同时适当的合成射流控制可以显著改善涡轮气动性能。

关键词：合成射流激励器水平轴风力机流动控制流动分离计算流体动力学

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Geotourism in the Salesopolis-Caraguatatuba Trail,Sao Paulo,Brazil:A Possibility to Utilize Geological Elements for Sustainable Development

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Journal of Environmental Protection 2013年第10期4卷 1044-1053页

作者： victor f.Velazquez Jose M.Azevedo Sobrinho Mikhaela A.J.S.Pletsch Antonio C.M.Guedes Gibby Zobel Escola de Artes Ciencias e HumanidadesUniversidade de Sao PauloSao PauloBrasil Instituto Geologico Secretaria do Meio Ambiente do Estado de Sao PauloSao PauloBrasil British Broadcasting Corporation LondonEngland

The Salesópolis-Caraguatatuba trail lies slightly more than 130 km to ESE from the Sao Paulo city, and it is fully inserted within the Atlantic forest. The region is particularly interesting because it brings together a complex lithological association and an exuberant topographical expression. A set of geological and geomorphological elements with high potentiality for the sustainable tourism development is documented in this paper. The geosites provide a wide variety of attraction, including valleys, streams, waterfalls and the unusual shapes of rocks. In each one of those outcrops, the visitors will have an exceptional opportunity for a better understanding about the processes that control the landscape evolution. In accordance with the new conception of geotourism, and taking as a basis the concepts of the geoscience for a rereading and interpretation of the several aspects of space and landscape, the sites catalogued should enable a new insight to increase environmental awareness of the local community, and, mainly, to encourage an innovative form of economic activity that has as a fundamental principle the nature preservation.

关键词： Salesopolis-Caraguatatuba Trail Geotourism Geosite Nature Preservation

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Early Proterozoic U-Pb Zircon Ages from Basement Gneiss at the Solovetsky Archipelago,White Sea,Russia

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International Journal of Geosciences 2012年第2期3卷 289-296页

作者： Stephan Schuth victor I.Gornyy Jasper Berndt Sergei S.Shevchenko Sergei A.Sergeev Alexandr f.Karpuzov Tim Mansfeldt Geographisches Institut Bodengeographie/BodenkundeUniversity of CologneCologneGermany Scientific Research Center for Ecological Safety Russian Academy of SciencesSaint-PetersburgRussia Institut fur Mineralogie Westfalische Wilhelms-Universitat MunsterMunsterGermany 4A.P.Karpinsky Russian Geological Research Institute(VSEGEI)Saint-PetersburgRussia 5Federal Agency of Mineral ResourcesMoscowRussia

The central region of the Neoarchaean Belomorian Mobile Belt (BMB) is, except for the Solovetsky Archipelago, largely covered by the White Sea. A newly discovered granitic gneiss outcrop on Solovetsky Island, Russia, enables a first age determination of the archipelago and evaluation of the hitherto poorly constrained central BMB. Zircons separated from the orthogneiss were analysed with SIMS-SHRIMP and LA-ICP-MS techniques. Both techniques yield a concordant U-Pb age of ca. 2.430 Ga, coinciding with ages of granitic intrusions in the BMB ca. 50 km west of the Solovetsky Islands.

关键词： Solovetsky Archipelago Granitic Gneiss Outcrop Age Determination 2.430 Ga

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On solvability of singular systems of quasilinear integro-diferential equations

On solvability of singular systems of quasilinear integro-di...

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2010 Chinese Control and Decision Conference

作者： Elena V.Chistyakova victor f.Chistyakov Milimir R.Pjescic Dragutin Lj.Debeljkovic Institute of system dynamics and control theory Siberian branch Russian academy of sciences IrkutskRussia

＜正＞General form of singular systems represented as a first order of quasilinear integro-differential first order vector equations is *** theorem of existence is proved and a numerical method of solution is proposed.

关键词： singular integro-differential-algebraic matrix pencil

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北美蛇绿岩杂岩体与硫化物矿化的关系

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地球与环境 1982年第3期 4-7页

作者： victor f.Hollister ,吴振寰冶金部情报研究总所

引言大量火山成因的硫化物矿床仅产出在少数北美蛇绿岩杂岩体中。但是有些经济地质学家推断大多数蛇绿岩杂岩体应当含有大量硫化物。本文介绍的大多数北美蛇绿岩杂岩体,和大多数现代扩张中心脊一样,几乎都是不含有大量硫化物的蛇绿岩... 详细信息

引言大量火山成因的硫化物矿床仅产出在少数北美蛇绿岩杂岩体中。但是有些经济地质学家推断大多数蛇绿岩杂岩体应当含有大量硫化物。本文介绍的大多数北美蛇绿岩杂岩体,和大多数现代扩张中心脊一样,几乎都是不含有大量硫化物的蛇绿岩杂岩体,同时,本文还将论述为什么有的蛇绿岩杂岩体含有硫化物,有的则不含有硫化物。典型的蛇绿岩杂岩体具有假地层的特征,其层序自下而上为:(1)超基性岩层的底层;(2)深成岩层,主要由辉长岩、闪长岩和辉绿岩所组成;(3)

关键词：蛇绿岩带枕状熔岩杂岩体深成岩侵入岩硫化物矿北美

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Determinants of mechanical restraint in an acute psychiatric care unit

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World Journal of Psychiatry 2021年第10期11卷 854-863页

作者： Khadija El-Abidi Antonio R Moreno-Poyato Alba Toll Privat David Corcoles Martinez Rosa Acena-Dominguez victor Perez-Sola Anna Mane Department of Psychiatry Institut de Neuropsiquiatria i AddiccionsParc de Salut MarBarcelona 08003Spain Public Health Mental and Maternal and Child HealthSchool of NursingFaculty of Medicine and Health SciencesUniversity of BarcelonaBarcelona 08907Spain Biomedical Research Institut Hospital del Mar d'Investigacions MediquesBarcelona 08003Spain Biomedical Research Center for Biomedical Research in Mental Health NetworkBarcelona 08003Spain Department of Psychiatry Institut de Neuropsiquiatria i AddiccionsCentre FòrumBarcelona 08019Spain

BACKGROUND Despite numerous attempts to reduce the use of mechanical restraint(MR),this technique continues to be widely applied in many acute psychiatric care *** order to reduce MR,a better understanding of the variables associated with its use and duration in different clinical environments is *** To determine the proportion of patients subjected to MR and the duration thereof in two acute care psychiatric units;and to identify the variables associated with the use and duration of *** Descriptive study of all patients admitted to the acute psychiatric units at the Parc de Salut Mar(Barcelona,Spain)in the year *** number and percentage of patients subjected to MR,as well as the duration of each episode were *** following data were also registered:sociodemographic characteristics,psychiatric diagnosis,and presence of cultural and/or language *** analyses were performed to assess determinants of MR and its *** Of the 464 patients,119(25.6%)required MR,with a median of 16.4 h per *** factors-a diagnosis of psychotic disorder[Odds ratios(OR)=0.22;95%CI:0.06-0.62;P=0.005]and the presence of a language barrier(OR=2.13;95%CI:1.2-3.7;P=0.007)-were associated with a significantly higher risk of *** sex was associated with a longer duration of MR(B=-19.03;95%CI:-38.06-0.008;P=0.05).CONCLUSION The presence of a language barrier and a psychotic disorder diagnosis are associated with a significantly higher risk of ***,male sex is associated with a longer duration of *** restraint protocols that include the required tools are necessary to ultimately limit the use of mechanical restraint.

关键词： Mechanical restraint Prolonged restraint Determining factors Psychiatric acute unit

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