Economic History eJournal最新文献

{"title":"On Hicks’s Failure to Grasp the Importance and Significance of the Keynes – Viner Exchanges Over the Extreme Elasticity - Instability of the LM(LP) Curve in Keynes’s February, 1937 Quarterly Journal of Economics","authors":"M. E. Brady","doi":"10.2139/ssrn.3323572","DOIUrl":"https://doi.org/10.2139/ssrn.3323572","url":null,"abstract":"Hicks’s April,1937 Econometrica article purported to provide a unique and different “interpretation” of Keynes’s liquidity preference theory of the rate of interest that centered on the highly elastic range of the LL (LM or LP) curve as being the central, critical and distinct element in Keynes’s liquidity preference theory of the rate of interest that was really original. Supposedly, this was not clearly discussed by Keynes in chapter 15 or anywhere else in the General Theory according to Hicks and the economists who followed Hicks.<br><br>However, a careful reading of pages 207-208 of the General Theory, combined with Keynes’s February, 1937 Quarterly Journal of Economics article reply to Viner’s claim that the LM curve had to be drawn as having a highly inelastic shape, published two months before Hicks’s Econometrica article, demonstrates that Hicks’s “interpretation” is identical to analysis presented by Keynes in the General Theory in 1936 on pages 207-208 and The General Theory of Employment in 1937.<br>The only unique accomplishment that Hicks made in his April,1937 Econometrica article is to have been the first economist to have actually drawn a LL (LM or LP) function with both highly inelastic and highly elastic ranges in Aggregate Income-rate of interest space that is identical to Keynes’s technical description on pp. 207-208 of the General Theory. His Figures are identical to the explicit, technical descriptions written by Keynes in the General Theory and The General Theory of Employment, where Keynes discussed the elasticities and shapes of the LM (LP) curve.<br>Hicks’s “interpretation” of IS-LM(LP) turns out to be identical to Keynes’s earlier analysis and conclusions, although Hicks failed to see the connection of Keynes’s work on IS-LM (LP) with the D-Z model of the Theory of Effective Demand that was the foundation for Keynes’s IS-LM (LP) model that was presented completely in chapter 21 in section four on pp.298-303 of the General Theory.<br><br>The correct historical description of the IS-LM model is the Keynes-Hicks-Hansen model and not the Hicks-Hansen IS-LM model. All introductory and intermediate macroeconomics textbooks, as well as all current history of economic thought perspectives on IS-LM, needed to be completely rewritten.<br><br>Current assessments of Keynes’s original role in the development and construction of the IS-LM model are due to a failure to read what Keynes clearly wrote in 1936 in the GT on pp.207-208 and on pp.218-219 in his GTE.Much of Hicks’s 1937 article is simply rewriting Keynes’s conclusions in different words. The only contribution Hicks made that had not been done by Keynes was to actually draw the curves.<br><br>","PeriodicalId":176096,"journal":{"name":"Economic History eJournal","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125861398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stock Earnings and Bond Yields in the US 1871-2016: The Story of a Changing Relationship","authors":"Valeriy Zakamulin, John A. Hunnes","doi":"10.2139/ssrn.3126321","DOIUrl":"https://doi.org/10.2139/ssrn.3126321","url":null,"abstract":"Using historical data that spans almost 150 years, we examine whether there is a long-run equilibrium relationship between the stock's earnings and bond yields. The novelty of our econometric methodology consists in using a vector error correction model where we allow multiple structural breaks in the equilibrium relationship. The results of our analysis suggest the existence of equilibrium relationship over 1871-1929 and 1958-2017. On the two historical segments, our analysis finds that the stock's earnings yield followed the bond yield in both the short- and long-run, but not the other way around. Perhaps the most important and surprising finding of our empirical study is that, after the break in 1929, a completely new equilibrium relationship re-emerged in 1958 that was later termed as the \"Fed model.\" Our main argument for the emergence of a new equilibrium relationship is that a major ``paradigm shift\" in the stock valuation theory occurred in the late 1950s. To support our argument, we highlight the main historical events that potentially could have caused the transition from the old to the new paradigm. Finally, we identify the primary impetus for the paradigm shift.","PeriodicalId":176096,"journal":{"name":"Economic History eJournal","volume":"148 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133721506","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Probability, Uncertainty, and Liquidity in the General theory (1936) and the General theory of Employment (1937) Always Comes in Degrees: Ergodicity-Nonergodicity Does not Come in Degrees","authors":"M. E. Brady","doi":"10.2139/ssrn.3314810","DOIUrl":"https://doi.org/10.2139/ssrn.3314810","url":null,"abstract":"Post Keynesians, starting with the work of Joan Robinson, G. L. S. Shackle, Sydney Weintraub, and Paul Davidson, have portrayed Keynes’s General Theory and Post General Theory work on the concepts of uncertainty and probability in strictly binary terms, like knowledge-unknowledge, certainty-uncertainty, open–closed, or ergodic-nonergodic.<br><br>There is no room for Keynes’s fundamental concept of degrees in these Post Keynesian binary representations, which directly conflict with Keynes’s constant categorization throughout his lifetime that probability, liquidity, liquidity preference, disquitetude and uncertainty came in degrees, simply means that Post Keynesians are not Keynesians. There are no binary concepts that appear in Keynes’s decision theory anywhere in anything that he published in his lifetime, be it the A Treatise on Probability, A Treatise on Money, General Theory, or The General Theory of Employment. <br><br><br>","PeriodicalId":176096,"journal":{"name":"Economic History eJournal","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121621627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On Paul Davidson’s Critique of Rational Expectations: Aiming at the Wrong Target Using the Wrong Theoretical Construct for the Wrong Reasons","authors":"M. E. Brady","doi":"10.2139/ssrn.3313222","DOIUrl":"https://doi.org/10.2139/ssrn.3313222","url":null,"abstract":"Paul Davidson’s nearly 40 years long critique of Rational Expectations is centered primarily on his claim that the Rational Expectations Hypothesis was built on a foundation that assumed ergodicity. However, the rational expectations hypothesis is not built on the assumption of ergodicity. The concepts of ergodicity and non-ergodicity belong to the Limiting Frequency interpretation of probability. Rational Expectations was supposed to have been built on the Subjective interpretation of probability. <br> <br>Rational Expectations is built on the claim, originally introduced in 1961 in R. Muth’s Econmetrica article, that the subjective probability distributions, for a given information set, are distributed around a true, correct, objective probability distribution. This assumption is incoherent, inconsistent, incomprehensible, and contradictory because there is no existing theory of probability (Classical, Logical, Propensity, Frequency, Subjective) that allows Subjective probabilities (distributions) to become equal to Objective probabilities (distributions). The only restriction allowed by the subjective theory of probability on the preferences of individual decision makers, which is applicable only at the micro level, is that the probabilities, be they initial or updated, are additive and linear. No other restriction is allowed by the Ramsey-Savage-de Finetti subjective Bayesian theory of probability. Rational expectation advocates, proponents, and practitioners add a very large number of additional restrictions on the subjective preferences of decision makers in order to transform subjective probability into an alleged true, correct, right objective probability (distribution). The fatal Achilles’ Heel of Rational Expectations is that there is no extant probability theory that allows subjective probabilities to be transformed into objective probabilities at the macro level or inter temporally throughout time. Savage made in very clear in 1954 in The Foundations of Statistics (p.16) that such an approach was “utterly preposterous” and “complete nonsense” since, as Bruno de Finetti had pointed out, “(objective) probability does not exist”. <br> <br>Paul Davidson’s critique completely overlooks the fundamental error committed in all theories of rational expectations, which is that at some point in time, subjective probabilities become objective probabilities. Nelson Goodman pointed out an additional, fundamental problem for the rational expectations approach of how this change can be expected to occur in the future, which was equivalent to his grue-bleen problems, where at some point in the future, empirically, well established green objects all of a sudden become blue or empirically, well established blue objects all of a sudden become green. <br><br>Paul Davidson’s critique of rational expectations is completely and fundamentally flawed because Davidson’s “ergodic-nonergodic” duality has absolutely nothing to do with the rational expectations' hy","PeriodicalId":176096,"journal":{"name":"Economic History eJournal","volume":"35 36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123323482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reaganomics: una línea divisoria (Reaganomics: A historical watershed)","authors":"J. Komlos","doi":"10.21789/24222704.1409","DOIUrl":"https://doi.org/10.21789/24222704.1409","url":null,"abstract":"Documentamos el impacto de la Reaganomics y su legado de largo plazo. Los datos indican que el crecimiento economico no fue particularmente impresionante despues de los recortes de impuestos de 1981. El PIB simplemente retorno al potencial y su tasa de crecimiento no fue superior a las tasas logradas en decadas anteriores o posteriores. Los supuestos incentivos de la economia de la oferta no se materializaron. La gente no trabajo mas, no ahorro ni invirtio mas, y el efecto de goteo fue insignificante, como el de la melaza. En cambio, la presidencia de Reagan fue una linea divisoria en el desarrollo economico de Estados Unidos en el sentido de que revirtio muchos de los logros del New Deal e inauguro una era en la que la desigualdad aumento sustancialmente, los salarios de los trabajadores poco calificados iniciaron un largo periodo de descenso y la participacion del trabajo en el PIB siguio disminuyendo. El legado de Reagan es una economia dual que acompano al deterioro de la clase media, la desregulacion que llevo a la crisis financiera, un enorme incremento de la deuda nacional, del 30% al 50% del pib, que no pudo ser detenido posteriormente y es superior al 100% en 2018, el antiestatismo que contribuyo al ascenso del trumpismo, un desmesurado aumento de la desigualdad que dio origen a una oligarquia y a una plutocracia, y el abandono de los trabajadores de overol que eventualmente se convirtieron en los deplorables de Hillary. En otras palabras, nada goteo hacia las mayorias. Los ricos y los super ricos recibieron todos los beneficios de los recortes de impuestos. Este es el verdadero legado de la economia de la oferta de la administracion Reagan.","PeriodicalId":176096,"journal":{"name":"Economic History eJournal","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115124098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Change and Persistence in the Age of Modernization: Saint-Germain-D&Apos;Anxure 1730-1895","authors":"G. Blanc, Romain Wacziarg","doi":"10.3386/w25490","DOIUrl":"https://doi.org/10.3386/w25490","url":null,"abstract":"Using a unique, comprehensive household-level dataset for a single French village from 1730 to 1895, we study the process of modernization during a period of rapid institutional and demographic transformation. We document changes in fertility, mortality, human capital and intergenerational mobility, looking for structural breaks associated with the French Revolution and paying close attention to the sequencing of changes associated with various aspects of modernization in the village. We find that the fall in fertility preceded the rise in education by several decades. Demographic change is plausibly associated with institutional and cultural change rather than with changes in the opportunity cost of children. The rise in education occurred mostly as the result of an increase in the supply of schooling due to the Guizot Law, rather than demand side forces. All these changes occurred in the absence of industrialization in and around the village. We conclude that institutional and cultural changes originating outside the village were likely the dominant forces explaining its modernization.","PeriodicalId":176096,"journal":{"name":"Economic History eJournal","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133995781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The IYLM Model Is a Pre-General Theory Model That Is Equivalent to Keynes’s mid 1934 Draft Copy Version","authors":"M. E. Brady","doi":"10.2139/ssrn.3306326","DOIUrl":"https://doi.org/10.2139/ssrn.3306326","url":null,"abstract":"Keynes ‘s General Theory has two separate, but interrelated models. Keynes called these models the D-Z and IS-LP(LM) models. The D-Z model deals only with expected results and outcomes. Expectations, uncertainty and confidence are dealt with by Keynes through his analysis of D=D1+D2 and Z=Z1 +Z2, where D1 measures expected consumption expenditures by consumers and D2 measures expected investment expenditures by businessmen based on Keynes’s Marginal Efficiency of Capital (mec) concept.<br><br>This model is built mathematically in chapters 20 and 21 of the General Theory after having been introduced briefly in chapter 3. Chapter 20 deals with the Goods and Labor markets. Keynes incorporates the Money market into the D-Z model on pp. 304-306 of the General Theory. The IS-LM(LP) model is an entirely separate model that deals with the actual or realized results of an economy. It is presented in its final form on pages 298-303 of the General Theory. Its form is Y=C+I, where C equals actual consumption expenditures and I equals actual investment expenditures. I has absolutely nothing to do with expectations or expected mec results. Keynes did not publish his December, 1933, four equation model presented in December 4th to his students or the very similar mid 1934 first draft copy of the General Theory because these models mixed up realized variables with expected variables.<br><br>The IYLM model of O’Donnell and Rogers (2016; Cambridge Journal of Economics) presents a model that is very similar to the earlier four equation models that Keynes realized were a conceptual breakthrough, but which were badly flawed mathematically and technically. Their IYLM model mixes up realized and expected results and does not make any sense mathematically because you can’t add realized consumption and expected investment to equal realized aggregate demand as done by O’Donnell and Rogers (2016). Their main error was their inability to recognize the interrelated, but separate nature of Keynes’s two models.<br><br>","PeriodicalId":176096,"journal":{"name":"Economic History eJournal","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131246574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Demand and Supply for Money [M=L(r) ] is not the Demand and Supply for Liquidity[M=M1plus M2=L1(Y) plus L2(r) {=L}","authors":"M. E. Brady","doi":"10.2139/ssrn.3294477","DOIUrl":"https://doi.org/10.2139/ssrn.3294477","url":null,"abstract":"A major confusion among economists ,who have been writing on the General Theory since 1936,is to confuse the Demand and Supply for Money [M=L(r) ] with the Demand and Supply for Liquidity[M=M1plus M2=L1(Y) plus L2(r) {=L}.<br><br><br>Chapter 13 of the General Theory concentrates exclusively on the second of the two constituents which, together, determine the equilibrium rate of interest. The first constituent, the mec and investment multiplier, determines the IS equation(curve). Keynes dealt with this in chapters 8-12 of the General Theory. Keynes made it very clear that in chapter 13 he was going to deal exclusively with the second constituent, liquidity preference ,which had been ignored by classical economists. Chapter 15 puts both of the constituents together .In Chapter 14 of the General Theory , Keynes demonstrated on pp.179-182 that the neoclassical theory of the rate of interest generated a single downward sloping curve in (Y,r ) space.Neoclassical theory had NO Liquidity Preference Function curve or what Hicks called LL and Hanson called LM.<br><br>The belief that Keynes’s theory of the rate of interest is denoted by <br><br>M=L(r),<br> <br>as argued by Hawtrey, Viner, Robertson, Robinson, and Ahiakpor, is false. Keynes’s theory of the rate of interest is given by three mathematical, simultaneous equations presented on pp.298-299 of the GT.The missing equation needed by the classical school is <br><br><br>M = M1 plus M2 = L1( Y) plus L2(r)[=L;author’s insert].<br><br><br>The equation M=L(r) is not the equation Harrod was talking about in his August 30th, 1935 letter to Keynes,a letter that Akiakpor had to have read in 1999 in preparation for his response to O’Donnell(1999).<br><br>It is impossible to graph M=L(r) in (Y,r) space<br><br><br>Only M = M1 plus M2 = L1( Y) plus L2(r)[=L;author’s insert] can be graphed in (Y,r) space.<br><br>Finally,Keynes incorporated the IS function implicitly into the Liquidity Preference Function by using L 1( Y).That allowed Keynes to talk about the demand and supply for liquidity,as opposed to the demand and supply for money.Keynes’s responses to Joan Robinson in late August –November,1936 concentrated on her complete misunderstanding of the theory of liquidity preference .It shows that Joan Robinson interpreted Keynes’s discussion of the demand and supply for liquidity as being the same thing as the demand and supply for money.<br><br>The demand and supply for money is not the same thing as the demand and supply for liquidity.<br><br><br><br>","PeriodicalId":176096,"journal":{"name":"Economic History eJournal","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117199231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lending a Hand: How Small Black Businesses Supported the Civil Rights Movement","authors":"L. Ferleger, M. Lavallee","doi":"10.2139/ssrn.3125212","DOIUrl":"https://doi.org/10.2139/ssrn.3125212","url":null,"abstract":"A large literature has detailed the seminal roles played in the Civil Rights Movement by activists, new political organizations, churches, and philanthropies. But black-owned businesses also provided a behind-the-scenes foundation for the movement’s success. Many black-owned businesses operated across the South because they provided goods and services to black customers who could not attain them from white businesses because of segregation. These small business owners very often played roles in civic matters that their counterparts in larger firms did not. Their civic participation and support contributed far more to the potential for political progress than scholars have recognized. Some accounts of the Montgomery Bus Boycott, for example, underestimate the significance of the role played by Montgomery`s community of black-owned businesses, from taxis to pharmacies. Examples from the Civil Rights Movement in Mississippi also illustrate the importance of local small businesses: black business owners were on the front lines, resisting strong pressures from the white community. This paper analyzes these episodes and places them in the context of black-owned businesses in the United States in the 1950s and 1960s, albeit descriptively given the unevenness and unavailability of standardized statistics. It also traces the debates over “Black Capitalism†and how the decline of segregation led to dramatic reorganizations of black businesses.","PeriodicalId":176096,"journal":{"name":"Economic History eJournal","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123986888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Kahn’s Mathematical Style, in His June, 1931 Multiplier Article in the Economic Journal, Is Identical to Keynes’ Style of Presenting Mathematical Results Starting in 1921 in the A Treatise on Probability","authors":"M. E. Brady","doi":"10.2139/ssrn.3286471","DOIUrl":"https://doi.org/10.2139/ssrn.3286471","url":null,"abstract":"The manner in which R. Kahn presented his mathematical results on the multiplier in the Economic Journal of June, 1931, is identical to the style of presenting mathematical results used by Keynes to present his mathematical analysis starting with the A Treatise on Probability in 1921. Keynes’s style was to present only the initial statement of the problem and the main, final results. Keynes assumed that the mathematically interested reader would have sufficient training to be able to work backwards from the final result that he had given to the intermediate steps. A mathematically trained reader would finally arrive at the initial conditions that had been set up to specify what the problem was.<br><br>This style is in contrast to all of the other presentations made by Kahn, who would incorporate intermediate steps.<br><br>The only conclusion which is possible is that Keynes, who was the editor of the EJ and probably the referee of Kahn’s paper, showed Kahn his analysis from the A Treatise on Probability in 1921 dealing with the problem of taking the limit of a geometrical series of declining, infinite numbers, so as to arrive at a finite sum for the series. The only difference between Kahn and Keynes is that Kahn uses the variable k, whereas Keynes used the variable q. Nowhere in his 1931 article does Kahn present any technical explanation of how he arrives at the limit value or provide any of the needed, intermediate steps required in order to arrive at the finite answer.","PeriodicalId":176096,"journal":{"name":"Economic History eJournal","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131182046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}