美国小型和大型商业银行的利润效率来源及差异及引力波的实验探测给我们的启示

本科毕业论文外文翻译外文题目：ProfitefficiencysourcesanddifferencesamongsmallandLargeU.Scommercialbanks出处：Journalofeconomicandfinance(2021):289-299作者：AigbeAkhigbeandJamesMcNulty原文：IntroductionScaleeconomiesinbankinghavelongbeenofinteresttofinancialeconomists,andthisinteresthasbeenheightenedinrecentyearsbytwodevelopments.Thefirstisincreasedconcernaboutthesurvivabilityofsmallcommunitybanksinaneraofbankconsolidation.ThisthemewasthesubjectofaMarch2021conferenceattheFederalReserveBankofChicagoandformedthebasisforaspecialMarch2021issueoftheJournalofFinancialServicesResearch.Theseconddevelopmentisrecentacademicresearchsuggestingthatsmallbanksmayhavebothaninformationadvantageoverlargebanks,asinNakamura(1993),Mester,Nakamura,andRenault(2021),andCarterandMcNulty(2021),andanincentivetousethisinformationadvantageinthelendingprocess.Bergeretal.(2021)provideevidenceonthesecondpoint.Theysuggestthatsmallbanksmayhaveacomparativeadvantageindevelopingandusingthe“soft”informationoftenassociatedwithsmallbusinesslending.PROFEFFisaneconometricfinancialperformancemeasurethatindicateshowactualfinancialperformancecomparestoatheoreticalbest-practicefrontier.Consideringdifferencesin,andsourcesof,profitefficiency(PROFEFF)bybanksizegroupscanhelpshedlightontheissueofwhichbanksusetheircapitalmoreefficiently(providedprofitsarenormalizedbyequity,whichistheapproachwetakeinthispaper).RelevantLiteratureandEstimationIssuesMoststudiesdoneinthe1980sandearly1990ssuggestthatscaleeconomiesareslightornonexistentbeyondassetsizesof$50to$100million.SomeearlyexamplesareBenston,Hanweck,andHumphrey(1982),Gilligan,Smirlock,andMarshall(1984),Clark(1984),Nelson(1985),andBerger,Hanweck,andHumphrey(1987).Using1984data,BergerandHumphrey(1991)findthateconomiesofscaleatthefirmlevelareexhaustedbeyond$200millioninassetsize.Sincethisinfluentialstudy,whichfoundthatgainsfromreducingcostinefficienciesdominategainsfromrealizingscaleeconomies,thefocusofmoststudieshasshiftedtoinefficienciesandhenceawayfromoptimumsize.However,usingcostefficiency,BergerandMester(2021)concludethatscaleeconomiesareexhaustedwellbefore$10billioninassetsize.Sincethesestudiesestimatecosteconomies,theycannotdirectlyaddressthepossibilitythatrevenuesmaybemorethanproportionatelyhigherforlargerbanks.However,anotherrelatedtrendinthisliteraturehasbeenincreasedrecognitionthatprofitefficiencyisamoreappropriatetechniquetouseinevaluatingbankperformancethancostefficiencysincePROFEFFincorporatesbothrevenuesandcosts.RecentprofitefficiencystudiesincludeAltunbas,Evans,andMolyneux(2021),AkhigbeandMcNulty(2021),BergerandMester(2021,2021),DeYoungandHasan(2021),andDeYoungandNolle(1996),amongothers.OtherrecentstudiesofU.S.bankingefficiencyincludeBarr,Kilgo,Siems,andStiroh(2021),Zimmel(2021),BergerandDeYoung(2021),andWheelockandWalker(2021,2021).Thekeynotepaperattheabove-mentionedconference,byDeYoung,Hunter,andUdell(2021),arguesthatsmallbanksandlargebankshaveadifferentfocusandadifferentbusinessmodel—personalizedserviceandcustomizedfinancialservices(e.g.,smallbusinessloans)inthecaseofsmallbanksandefficientdistributionofrelativelyuniformtypesoffinancialservices(e.g.,creditcardsandhomeequityloans)inthecaseoflargebanks.Thebusinessmodelofthesmallbankrequiresrelativelyhighcost,whilelargerbankscankeepcostlow.Underthislineofreasoning,bothtypesofbanksshouldhavearoletoplayinthefuturefinancialservicesmarketplace.Nonetheless,differencesinPROFEFFareimportantbecauseultimatelysmallandlargebankscompeteforcapital.Forexample,thedecisionofasmallerbanktojoinornottojoinalargebankingorganizationthroughamergerisultimatelyasubjectivedecisionabouthowitscapitalcanbebestemployed.Giventheseconsiderations,twoimportantquestionsraisedbyBergerandMester(2021)mustbeconsideredbeforeweproceed.Thefirstistheappropriatevariable—assetsorequity—touseinnormalizingprofitsincomputingthePROFEFFmeasure.Thesecondistheuseofonefrontierorseveralfrontiersincomparingbanksofdifferentsizes.BecausePROFEFF,whennormalizedbyequity,measureshowwellabankutilizesitsfinancialcapital,wechoosetousethismeasure.Someearlierstudiescomparinglargeandsmallbanks,suchasAkhigbeandMcNulty(2021),useassetsandfindsmallbankshavehigherPROFEFF.Useofequitycanbeexpectedtoproducetheoppositeresultsincelargebanksusemoreleveragethansmallbanks.Inotherwords,thePROFEFFmeasurethatweuseisclosertoreturnonequity,whichshouldshowgreaterPROFEFFforlargebanks.Normalizingbyassetsislikelytoproducetheoppositeresult.SincewewanttoconsiderthesourcesofthedifferencesinPROFEFF,weusethreedifferentfrontiersforsmall,medium,andlargebanks.Thisisconsistentwiththeassumptionthattheirfocus,andtheirbasicbusinessmodel,isdifferent.ThisprocedureallowsthePROFEFFmeasurestohavemaximumflexibility—smallbankPROFEFFanditsfrontierarenotconstrainedoraffectedinanywaybytheactivitiesandbalance-sheetstructureoflargebanks,andviceversa.Thus,whenwelookatthedeterminantsofPROFEFFforthethreegroups,iftheyaredifferent,thiswillreflectrealdifferences,andiftheyarethesame,itwillnotbebecausethesamefrontierwasimposedonallbanks.Werecognizethealternativeargumentthat,incomparingtheperformanceofdifferentbanks,onenormallywantstousethesametest,nottwoorthreedifferenttests.(Wemadethisargumentourselvesinanearlierpaper.)ProfitEfficiencyTrendsforVariousBankSizeGroupsPROFEFFhasdeclinedsharplyinrecentyearsforsmallbanks,from0.778in1995to0.702in2021.Weconsiderthehypothesisthatthisdeclinemayreflectanincreasingnumberofdenovobanksinthesmallbankcategory.FDICdataindicatethatbetween1992and1994only74newbanksperyearwerechartered,whichnodoubtreflectsthedepressedstateofthebankingindustryatthattime.Incontrast,inthesixyearperiodfrom1995to2021,therewereanaverageof175newbankchartersperyear.Manyofthesebanksremainsmallforanumberofyearsafterbeingchartered.DeYoungandHasan(2021)showthatdenovobanksaremuchlessprofitefficientthanolder,similarlysizedbanks.InTable1thepercentofbanksintheunder$100milliondollarcategorythataredenovos(ageunder10years)hasincreasedfrom11.4percentto13.5percent.Moreover,DeYoungandHasan(2021)showthatthefirstthreeyearsofoperationsshowparticularlylowPROFEFFfornewbanks.Thegreaterdispersionofthedataforsmallbanksinrecentyearsalsosupportsthisexplanation.Thus,thehypothesisthatatleastpartofthedeclineinsmallbankPROFEFFbetween1995and2021reflectstheperformanceofthedenovobanksinthesampleappearsreasonable.Incontrasttothesmallbanks,PROFEFFisrelativelystableformedium-sizeandlargebankswhentrendsinbothmedianandmeanvaluesaretakenintoaccount.Forexample,meanPROFEFFformediumsizebanksremainsabove0.81throughouttheperiodandlargebankPROFEFFremainsabove0.84.Nonetheless,somedeclineisevidentintheestimates,whichprobablyreflectsinpartthefactthatbanksinallsizegroupsareusinglessleveragebecauseofpressuresfromregulatorstoincreasetheamountofequitycapitalontheirbalancesheet.ResultsoftheRegressionAnalysisoftheCorrelatesofProfitEfficiencyAsnoted,weconsiderdifferencesinthesignificanceofthecorrelatesamongthesizegroupsasanindicationthatbanksofdifferentsizeshavedifferentwaysofachievinghighprofitability.Theequity/assetsratio(EQUITY)isnegative(asexpected)andsignificantatmediumandlargebanks.Thisindicatesthat,withinthesesizegroups,themoreprofit-efficientbanks,ceterisparibus,usemoreleverage(lessequity)thantheotherbanksinthesamesizegroup.Ageispositiveandsignificantforsmallandmedium-sizebanksbutnotforlargeones.Thiswouldbeconsistentwiththenotionthattheestablishmentofastrongcreditcultureisanimportantelementinsmallandmedium-sizebankprofitability.Overlappinggenerationsofloanofficers(eachgenerationtrainingthenextintheartofmakingloansinthelocalcommunity)andrelationshipdevelopmentareimportantelementsindevelopingsuchaculture.Successfulimplementationofthesestrategieswouldrequirethatthebankbeinexistenceforaconsiderableperiodoftime.Thisisthe“learningbydoing”discussedbyBergerandMester(2021)andmentionedabove.Themarketplacenonperformingloanratio(MKTNPL)issignificantwiththeexpectednegativesignforsmallandmedium-sizedbanksbutisactuallypositiveforlargebanks.Thisratioisnotparticularlyrelevantforlargerbankssinceitonlyconsidersnonperformingloansinthecountywherethehomeofficeofthebankislocated;mostlargebankshaveofficesandloansinmorethanonecounty.Membershipinamultibankholdingcompany(MBHC)isnegativeandsignificantforsmallandmedium-sizebanksbutnotforlargeones.Apparentlythemostsuccessfulsmallandmediumsizedbanksareindependent.Italsosuggeststhatlargebanksthataremembersofholdingcompaniesarelesslikelytobeaffectedbydevelopmentsattheholdingcompanylevelthanarethesmallerandmedium-sizedholdingcompanymembers.Therelativenonperformingloanratio(RELNPL)issignificantandnegativebutonlyformedium-sizebanks.Differencesinfeerevenue(FEEREV)areanimportantsourceofdifferencesinprofitabilityatsmallandmedium-sizebanks(notetheveryhighsignificancelevels)butnotatlargerones.Themostlikelyexplanationforthisisthatvirtuallyalllargebanksdependonfeerevenueratherthanthatfeerevenueisunimportantforthesebanks.[SeeTable1.]Theyeardummyvariablesarealsosignificantforsmallandmedium-sizebanksonly.Thissuggeststhatlargerbankshavemoreconsistentprofitabilityovertimethantheotherbanks.Competitiveconditionsmatterbutonlyforthetwosmallersizegroups.DifferencesinPROFEFFamongsmallbanksarepositivelyrelatedtotheHHI.Inotherwords,ceterisparibus,PROFEFFishigherinmoreconcentratedmarkets,whichisexactlywhatwewouldexpect.Thesamerelationshipholdsformedium-sizebanksbutnotforlargeones.BergerandMester(2021)andAkhigbeandMcNulty(2021)alsofindapositiverelationshipbetweenPROFEFFandtheHHI.Inaddition,mostofthecoefficientsoftheothercorrelatesareconsistentwiththefindingsofAkhigbeandMcNulty(2021).Thefactthatbanksofdifferentsizeattainhigh(orlow)profitefficiencythroughdifferentmeansisconsistentwiththeabove-mentionedrecentanalysisofDeYoung,Hunter,andUdell(2021)thatsuggeststhatbanksofdifferentsizeshavedifferentbusinessmodels.SummaryandConclusionsWeexaminethedifferencesinprofitefficiencyatsmall(under$100millioninassets),mediumsize($100millionto$1billion)andlarge(morethan$1billion)banksfortheperiod1995to2021,andwealsoexaminethesourcesofthesedifferences.SincewecalculatePROFEFFnormalizedbyequity,itisnotsurprisingthatlargebanksrankhighest.However,thedifferencesarequitelarge.Fortheperiodasawhole,averagePROFEFFis0.752forthesmallbanks,0.823forthemedium-sizebanks,and0.856forthelargebanks.Inotherwords,thedifferencebetweensmallandlargeismorethan10basispoints,whichiseconomically(andstatistically)quitesignificant.SmallbankscanattainhighPROFEFFbybeingolder,byoperatinginmarketswithlowdefaultrates,bybeingindependentofaholdingcompany,bygeneratinghighfeeincome,byoperatinginaconcentratedmarket,andbyhavingmoreoftheirassetsinloansasopposedtosecurities.LargebanksthathavehighPROFEFFdosoprimarilybyusingmoreleveragesincenoneoftheothervariablesaresignificant.DeYoung,Hunter,andUdell(2021)arguethatdifferenttypesofbankshavedifferentbusinessmodels.Thebusinessmodelofthesmallbankiscustomizedandpersonalizedservicebutathighcost,whilelargerbanksaimtodeliverrelativelyuniformfinancialservicestolargegroupsofcustomersatlowercost.Ouranalysisisconsistentwiththisnotionthatdifferenttypesofbanksattainhighprofitabilityindifferentways.译文：美国小型和大型商业银行的利润效率来源及差异简介金融经济学家一直对银行的规模经济很感兴趣，近几年，由于两次发展而对银行规模经济的这个兴趣进一步的加深。首先是增加对银行合并时代的小型社区银行的关注。这个主题是在2021年3月的一个美国芝加哥联邦储蓄银行会议的主题，形成了一个2021年3月的特殊的金融服务研究杂志的基础。第二个发展是最近的学术研究，表明了小银行可能比大银行更有信息的优势（1993），同在中村，美斯特，中村，雷诺（2021），卡特和麦克纳尔蒂（2021年），鼓励使用贷款过程中的这种信息优势。柏格等（2021）提供了第二点证据，他们认为，小型银行在发展和利用“软”信息时可能具有的一个比较优势往往与小企业贷款相关。利润效率是指示如何比较实际财务业绩和最佳实践前沿理论的计量财务绩效的衡量。考虑到差异以及来源，银行规模组的盈利效率可以帮助解决银行更有效的使用他们的资本的这个问题（提供的利润归一股权，这是我们在本文采取的方法）。相关的文献和估计问题在80年代和90年代初所做的大多数研究表明，资产规模在5000万美元至1亿美元的规模经济是轻微的或是不存在。利用1984年的数据，伯杰和汉弗莱（1991）发现资产规模在2亿美元以上的规模经济在企业层面已经枯竭。由于这个有影响力的研究，从而发现从降低成本的低效率的收益来主宰实现规模经济的收益。大多数研究的焦点已经转移到低效率，从而远离了最佳规模。但是，使用成本效益，伯杰和美斯特（2021）的结论是规模经济用尽之前的资产规模是100亿美元。由于成本经济的估计研究，他们不能直接解决大型银行可能有比例较高的收入问题的可能性。然而，这些文献中的另一个相关趋势已进一步的认识到，利润效率使用在银行业绩评价中比成本效益更合适，因为利润效率既包含收入又包含费用。近期的利润效率研究包括Altunbas,Evans,和Molyneux(2021),Akhigbe和McNulty(2021),Berger和Mester(2021,2021)DeYoung和Hasan(2021)和DeYoung和Nolle(1996)等。最近其他的美国银行效率的研究包括了Barr，Kilgo，Siems和Stiroh（2021），Zimmel（2021），Berger和DeYoung（2021）和Wheelock和Walker（2021,2021）.DeYoung,Hunter和Udell（2021）在上述会议主题文件中认为，小型银行和大型银行有着不同的重点和不同的商业模式——小银行的情况是个性化服务和客制化的金融服务（例如，小企业贷款），而相对于大型银行来说则是分布比较均匀类型的高效金融服务（例如，信用卡和房屋净值贷款）。小型银行的业务模式需要的成本相对较高，而大银行可以保持低成本。根据这种推论，这两种类型的银行在未来金融服务市场上都有一个发挥的角色。然而，在利润效率中的差异是很重要的，因为最终小型银行和大型银行竞争的是资本。例如，一个较小的银行决定通过合并加入或者不加入一个大型的银行机构，最终是关于它们的资本如何能最好使用的主观决定。鉴于这些因素，由美斯特和伯杰（2021）提出的两个重要问题在我们开始之前必须考虑。第一个是相应的变量——资产或权益——使用正常化利润计算利润效率的措施。第二个则是利用一个或者几个前沿领域比较不同规模的银行。由于利润效率，股权归一时，一个银行如何利用好它们的金融资本的措施，我们选择使用这项措施。一些早期的研究利用资产比较大型和小型银行的，例如Akhigbe和McNulty（2021），发现小银行具有较高的利润效率。利用股权可预期产生相反的结果，因为大型银行比小银行有更好的杠杆作用。换句话说，我们使用的利润效率的措施更接近净资产收益率，这表现出大型银行有更大的利润效率。资产正常化可能产生相反的结果。由于我们要考虑利润效率差异的来源，我们使用小型，中型和大型银行的三个不同的领域。这与假设一致，它们的焦点，它们的基本经营模式是不同的。这个程序允许利润效率措施有最大的灵活性——小银行的利润效率不受大银行的活动和资产负债表结构的任何约束或影响，反之亦然。因此，当我们看到这三个群体的利润效率的决定因素，如果它们是不同的，这将反应真正的差别，如果它们是相同的，所有的银行将不会因为相同的前沿被制裁。我们认识到的另一类说法是，在比较不同银行的业绩时，人们通常想要使用相同的测试，而不是两个或者三个不同的测试。（先前的文章中我们自己讨论过这个论点）各种规模的团体银行的利润效率趋势近几年来，小型银行的利润效率急剧下降，从1995年的0.778下降到2021年的0.702。我们认为这种下降的假设可能反映了在小银行类别中的从头银行数量的增加。联邦存款保险公司的数据表明，在1992年和1994年之间，每年只有74家特许的新银行，这无疑反映了当时银行业的低迷状态。与此相反，在从1995年至2021年的六年时间里，平均每年有175家特许成立的银行。许多银行在特许成立之后的很多年规模仍然很小。DeYoung和Hasan（2021）表明，从头银行的利润效率比老的，相同规模的银行的利润效率少得多。表1中在一亿美元以下的银行类别的百分比中从头银行（未满10年）已经从百分之11.4上升到百分之13.5。此外，DeYoung和Hasan（2021）指出，新银行前三年的经营显示出的利润效率特别低。近几年，数据更加分散的小银行也支持这个解释。因此，在1995年至2021年的小型银行至少部分利润效率下降的假设反映了从头银行在样本中出现的合理性。与小型银行相反，当把中位数和均值的趋势都考虑在内时，中型银行和大型银行的利润效率相对稳定。举例来说，意味着在整个期间内中型银行的利润效率高于0.81而大型银行的利润效率仍高于0.84。然而，在估计中有所下降是显而易见的，这可能在某种程度上反映了一个事实，银行在所有规模团体中较少使用杠杆是因为来自监管机构的压力增加了他们的资产负债的资本金额。利润效率的回归的相关性分析结果如前所诉，我们考虑相关的意义之间差异的大小作为一组相关指示，不同规模的银行有不同的方式来实现高盈利的能力。在中型和大型银行中股本/资产的比率（股权）为负的（如预期），而且是显著的。这表明了，在其他条件不变时，更多利润，高效率的银行在这些相同的大小团体中比其他的银行使用了更多的杠杆（较少的权益）。对于小型银行来说年龄是积极的，重要的，但是对大型银行而言不是。这是个一致的概念，一个强有力的信用文化的建立是中小银行盈利的重要因素。信贷员的世代重叠（在当地社区，每一代的培训下发放贷款）和关系的发展，是建立这样一种文化的重要元素。这些战略的成功实施将要求银行存在相当长的时间。这就是美斯特（2021）讨论的“从做里面学习”，如上所诉。中小银行的不良市场贷款率（MKTNPL）是显著的，与预期的一样是负的，但是实际上对于大银行来说是正的。这个比例对较大的银行来说不是特别重要，因为它仅考虑家庭办公所在地县级那里的银行的不良贷款。多数的大银行有一个以上的县办事处和贷款。对于中小银行来说，会员在一家销售控股公司（MBHC）是具有消极的意义和作用的，但对于大银行来说不是。显然，最成功的中小银行是独立的。它还表明了，大型银行控股公司的成员不太可能受到控股公司发展水平的影响，而中小银行控股公司的成员可能受到的影响较大。相对的不良贷款比例（RELNPL）是显著的复数，但仅仅是对中型银行而言。在中小银行中，费用收入的差异是盈利能力差异的一个重要来源（注意显著性水平非常高），但是对于大型银行来说不是。对此最可能的解释是，几乎所有大型银行都依赖费用收入，而不是说费用收入对这些银行不重要。(见附表1)年的虚拟变量也只对中小银行具有重要的意义。这表明，随着时间的推移大型银行比其他的银行具有更多持续的盈利能力。竞争条件很重要，但仅仅是对两个较小的组织而言。小银行之间的利润效率的差异与赫芬达尔指数是正相关的。换句话说，在其他条件不变时，市场越集中，利润效率就越高，而这也正是我们所期望的。与此有同样关系的是中型银行，大型银行则不适合。BergerandMester(2021)andAkhigbeandMcNulty(2021)也发现了利润效率与赫芬达尔指数之间的正相关的关系。此外，对其他大部分的相关系数的研究与AkhigbeandMcNulty(2021)的研究结果是一致的。事实上，不同规模的银行要通过不同的方式实现高（或者低）的利润效率是符合上述DeYoung,Hunter和Udell(2021)的分析的，不同规模的银行要有不同的商业模式。总结和结论我们研究了1995年至2021年期间的小型银行（资产低于一亿美元），中型银行（一亿美元至十亿美元）和大型银行（十亿美元以上）之间利润效率的差异，以及这些差异的来源。由于我们采用权益计算正常化的利润效率，所以大银行的排名最高也就不足为奇。但是，这些差异都相当的大。对于整个的期间，小型银行的平均利润效率是0.752，大型银行的平均利润效率是0.823，而大型银行的平均利润效率0.856。换句话说，小型银行与大型银行的利润效率差距超过了10个基点，这在经济上（和统计上）是相当显著的。小型银行可以通过成长，通过低违约率的市场运作，通过成为独立的控股公司，通过产生高的费用收入，通过在一个集中的市场中经营和通过贷款来获取更多自己的资产而不是有价证券来达到高的利润效率。大型银行主要是通过使用更多的杠杆来实现高的利润效率，这是因为其他变量都是没有意义的。DeYoung,Hunter和Udell(2021)指出了不同类型的银行有着不同的商业模式。小型银行的商业模式是客定制的和个性化的服务，但是成本高；而大型银行的目标则是对庞大的客户群体在较低的成本下提供相对统一的金融服务。我们的分析与不同类型的银行以不同的方式实现高盈利能力的这个概念是一致的。hinese

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survey.In

about

one

month,

a

questionnaire

compiled

by

top

eye

care

medical

experts

in

China

willbe

distributed

through

multiple

online

partners,

including

H,

as

well

asthrough

offline

survey

events

held

in

universities,

middle

schools

and

primary

schools

acrossthe

country.A

report

will

be

released

based

on

the

survey

statistics

and

analysis,

and

most

importantly,guidelines

for

parents

and

youth

on

how

to

care

for

the

eyes

and

prevent

myopia

—

agrowing

problem

in

China's

digitized

society,

will

also

be

attached

on

the

report."Myopia

is

not

only

a

disease

that

makes

people

see

things

blurrily,

but

also

leads

to

severecomplications,

such

as

glaucoma

(increased

pressure

within

the

eyeball),

and

can

causeblindness,"

said

Zhou

Yuehua,

an

established

eye

care

specialist

with

Beijing

TongrenHospital."It

is

very

important

for

parents

and

children

to

know

about

the

risk

and

care

for

their

eyes."There

are

about

450

million

myopia

patients

in

China.

Among

Chinese

myopia

patients,30hinese

pharmaceutical

company,

jointlyannounced

the

kickoff

of

the

survey.In

about

one

month,

a

questionnaire

compiled

by

top

eye

care

medical

experts

in

China

willbe

distributed

through

multiple

online

partners,

including

H,

as

well

asthrough

offline

survey

events

held

in

universities,

middle

schools

and

primary

schools

acrossthe

country.A

report

will

be

released

based

on

the

survey

statistics

and

analysis,

and

most

importantly,guidelines

for

parents

and

youth

on

how

to

care

for

the

eyes

and

prevent

myopia

—

agrowing

problem

in

China's

digitized

society,

will

also

be

attached

on

the

report."Myopia

is

not

only

a

disease

that

makes

people

see

things

blurrily,

but

also

leads

to

severecomplications,

such

as

glaucoma

(increased

pressure

within

the

eyeball),

and

can

causeblindness,"

said

Zhou

Yuehua,

an

established

eye

care

specialist

with

Beijing

TongrenHospital."It

is

very

important

for

parents

and

children

to

know

about

the

risk

and

care

for

their

eyes."There

are

about

450

million

myopia

patients

in

China.

Among

Chinese

myopia

patients,30hinese

pharmaceutical

company,

jointlyannounced

the

kickoff

of

the

survey.In

about

one

month,

a

questionnaire

compiled

by

top

eye

care

medical

experts

in

China

willbe

distributed

through

multiple

online

partners,

including

H,

as

well

asthrough

offline

survey

events

held

in

universities,

middle

schools

and

primary

schools

acrossthe

country.A

report

will

be

released

based

on

the

survey

statistics

and

analysis,

and

most

importantly,guidelines

for

parents

and

youth

on

how

to

care

for

the

eyes

and

prevent

myopia

—

agrowing

problem

in

China's

digitized

society,

will

also

be

attached

on

the

report."Myopia

is

not

only

a

disease

that

makes

people

see

things

blurrily,

but

also

leads

to

severecomplications,

such

as

glaucoma

(increased

pressure

within

the

eyeball),

and

can

causeblindness,"

said

Zhou

Yuehua,

an

established

eye

care

specialist

with

Beijing

TongrenHospital."It

is

very

important

for

parents

and

children

to

know

about

the

risk

and

care

for

their

eyes."There

are

about

450

million

myopia

patients

in

China.

Among

Chinese

myopia

patients,30hinese

pharmaceutical

company,

jointlyannounced

the

kickoff

of

the

survey.In

about

one

month,

a

questionnaire

compiled

by

top

eye

care

medical

experts

in

China

willbe

distributed

through

multiple

online

partners,

including

H,

as

well

asthrough

offline

survey

events

held

in

universities,

middle

schools

and

primary

schools

acrossthe

country.A

report

will

be

released

based

on

the

survey

statistics

and

analysis,

and

most

importantly,guidelines

for

parents

and

youth

on

how

to

care

for

the

eyes

and

prevent

myopia

—

agrowing

problem

in

China's

digitized

society,

will

also

be

attached

on

the

report."Myopia

is

not

only

a

disease

that

makes

people

see

things

blurrily,

but

also

leads

to

severecomplications,

such

as

glaucoma

(increased

pressure

within

the

eyeball),

and

can

causeblindness,"

said

Zhou

Yuehua,

an

established

eye

care

specialist

with

Beijing

TongrenHospital."It

is

very

important

for

parents

and

children

to

know

about

the

risk

and

care

for

their

eyes."There

are

about

450

million

myopia

patients

in

China.

Among

Chinese

myopia

patients,30hinese

pharmaceutical

company,

jointlyannounced

the

kickoff

of

the

survey.In

about

one

month,

a

questionnaire

compiled

by

top

eye

care

medical

experts

in

China

willbe

distributed

through

multiple

online

partners,

including

H,

as

well

asthrough

offline

survey

events

held

in

universities,

middle

schools

and

primary

schools

acrossthe

country.A

report

will

be

released

based

on

the

survey

statistics

and

analysis,

and

most

importantly,guidelines

for

parents

and

youth

on

how

to

care

for

the

eyes

and

prevent

myopia

—

agrowing

problem

in

China's

digitized

society,

will

also

be

attached

on

the

report."Myopia

is

not

only

a

disease

that

makes

people

see

things

blurrily,

but

also

leads

to

severecomplications,

such

as

glaucoma

(increased

pressure

within

the

eyeball),

and

can

causeblindness,"

said

Zhou

Yuehua,

an

established

eye

care

specialist

with

Beijing

TongrenHospital."It

is

very

important

for

parents

and

children

to

know

about

the

risk

and

care

for

their

eyes."There

are

about

450

million

myopia

patients

in

China.

Among

Chinese

myopia

patients,30

a您好，为你提供优秀的毕业论文参考资料，请您删除以下内容，O(∩_∩)O谢谢！！！A

national

survey

was

recently

launched

to

evaluate

the

eye

health

of

Chinese

children

andteenagers.On

June

6,

China's

annual

National

Day

for

Eye

Care,

the

China

Youth

Development

ServiceCenter

and

Zhejiang

Medicine,

a

leading

listed

Chinese

pharmaceutical

company,

jointlyannounced

the

kickoff

of

the

survey.In

about

one

month,

a

questionnaire

compiled

by

top

eye

care

medical

experts

in

China

willbe

distributed

through

multiple

online

partners,

including

H,

as

well

asthrough

offline

survey

events

held

in

universities,

middle

schools

and

primary

schools

acrossthe

country.A

report

will

be

released

based

on

the

survey

statistics

and

analysis,

and

most

importantly,guidelines

for

parents

and

youth

on

how

to

care

for

the

eyes

and

prevent

myopia

—

agrowing

problem

in

China's

digitized

society,

will

also

be

attached

on

the

report."Myopia

is

not

only

a

disease

that

makes

people

see

things

blurrily,

but

also

leads

to

severecomplications,

such

as

glaucoma

(increased

pressure

within

the

eyeball),

and

can

causeblindness,"

said

Zhou

Yuehua,

an

established

eye

care

specialist

with

Beijing

TongrenHospital."It

is

very

important

for

parents

and

children

to

know

about

the

risk

and

care

for

their

eyes."There

are

about

450

million

myopia

patients

in

China.

Among

Chinese

myopia

patients,30million

are

severe

patients,

according

to

ZhouThe

prevalence

of

myopia

among

high

school

and

college

students

is

more

than

70

percent,and

the

situation

is

continuously

worsening,

he

added.Sun

Zhu,

director

with

the

China

Youth

Development

Service

Center,

said

long

hours

ofstudy,

lack

of

exercise,

especially

outdoor

activities,

and

attachment

to

electronic

screen

aresome

of

the

top

reasons

behind

the

widespread

myopia

problems,

and

the

increase

ofyounger

patients,

although

China

has

made

great

progress

in

improving

the

hardwarefacilities

and

lighting

conditions

in

schools.He

said

he

hopes

the

survey

will

alert

people

on

the

threatening

situation,

and

also

helpmedical

experts

to

better

guideline

parents

and

children's

behaviors

to

care

for

eyes,

basedon

the

timely

and

factual

statistics

the

survey

collected.A

series

of

follow-up

events

will

also

be

held

in

six

cities,

including

Jinan

in

Shandongprovince,

and

Changsha

in

Hunan

province,

to

educate

people

on

how

to

care

for

eyes

afterthe

survey

started.MoreandmoreChinesearejoggingtogetandstayfit.Mostjoggerswillrunalone,butsomewilljogwithfriendsorevencoaches.TheBeijingOlympicForestParkisoneofthemostpopularspots.Itispackedwithrunnersintheafternoon,usuallyafterwork,andatweekends.Joggingafterawholeday'sworkcanbeawaytounwind.ItistrueforHeWenjun,whoseworkplaceisrightneartheforestpark.Shediscoveredherathleticaptitudeattheageofseven,whenshebeganplayingtennis.Thensheturnedtojogging,andshehasperseveredwithitfor10years."Icometojogalmosteverydayafterwork,wheneverIhavetime.Ithinkjoggingisgoodformyhealth.Andforme,agirl,ithelpsmetoachievetoeternalgoal,tokeepslim,"Hesaid.Hesayssheprefersjoggingalone,soshecanfocusbetter.Shelovesjogging,evenduringBeijing'ssmoggydays."Ifthesmogissevere,I'llholdoffjoggingforawhile.ButifIreallywanttogetawayfromwork,I'llwearamask,orjustignorethesmogandgoonjogging,"shesaid.Forthosewhoarenotsoathletic,jogg

引力波的实验探测给我们的启示摘要：引力理论的发展经历了数百年，从牛顿到爱因斯坦，从万有引力定律到广义相对论。在这过程中，科学家们引力波的预言质疑不休、争论不止。而引力波的实验探测无疑证明了一切。引力波的发现，弥补了爱因斯坦的广义相对论的漏洞，也确定了他的理论的正确。这是人类史上出现的又一契机，它将为人类社会带来重大变革。“破五”是中国传统迎财神的日子。2016年的这一天，却一个让全世界物理学界沸腾的日子，甚至许多的物理学家为之痛哭流涕——被预言已经百年的引力波，终于被探测到了。引力是什么？在今天人们所知道的物质的四种基本相互作用中，引力作用为最弱。四种相互作用按作用强度比例顺序是：强相互作用(1),电磁相互作用(10),弱相互作用(10),引力相互作用(10)。因此，在研究基本粒子的运动时，引力一般略去不计。但在天文学领域内，由于涉及的对象的质量极其巨大，引力就成为不仅支配着天体的运动，而且往往是天体的结构和演化的决定因素。引力并不是一种所谓的“力”，而是一种属性。牛顿在1687年出版的《自然哲学的数学原理》一书中首次提出万有引力定律，基于此，他结识了彗星的运动