Unraveling the dynamics of growth, aging and inflation for citations to scientific articles from specific research fields

We analyze the time evolution of citations acquired by articles from journals of the American Physical Society (PRA, PRB, PRC, PRD, PRE and PRL). The observed change over time in the number of papers published in each journal is considered an exogenously caused variation in citability that is accounted for by a normalization. The appropriately inflation-adjusted citation rates are found to be separable into a preferential-attachment-type growth kernel and a purely obsolescence-related (i.e., monotonously decreasing as a function of time since publication) aging function. Variations in the empirically extracted parameters of the growth kernels and aging functions associated with different journals point to research-field-specific characteristics of citation intensity and knowledge flow. Comparison with analogous results for the citation dynamics of technology-disaggregated cohorts of patents provides deeper insight into the basic principles of information propagation as indicated by citing behavior.Comment: 13 pages, 6 figures, Elsevier style, v2: revised version to appear in J. Informetric

Recognizing Risk in Human Capital Investments: A Real Options Approach to Strategic Human Resource Management

An issue that has not yet been explored in the field of strategic human resource management (SHRM) is that of managing the ‘risks’ involved in human capital management of the firm. We address this issue using the real option theory framework. We argue that certain HR practices manage risk and generate opportunities for the firm by creating \u27options\u27 for its human capital management. These HR options help ensure stability of returns from human capital and thus sustain competitive advantage. Different types of HR options and the role of certain HR practices in creation of these options are discussed

The Theorem of Proportionality in Mainstream Capital Theory: An Assessment of its Applicability

This paper surveys and assesses the empirical literature that bears on the applicability of the theorem of proportionality, which asserts that depreciation is proportional to the outstanding capital stock. All available evidence shows that: a) the rates of depreciation and retirements vary from year to year in response to changes in conventional economic forces like utilization, maintenance and repair, the prices of new capital goods, etc., and b) while the approximation of the distribution of depreciation rates by a single parameter may be characterized by simplicity and ease of use, at the same time it thwarts the advances that can be achieved by returning to a general equilibrium model centered on the time structure of capital and the useful lives of its components. For this reason, it is concluded that, the sooner this theorem is replaced by an endogenous theory of depreciation and replacement, the better for economic theory and policy.Capital longevity, replacement, depreciation, scrappage, maintenance, utilization, obsolescence

The Bibliometric Properties of Article Readership Information

The NASA Astrophysics Data System (ADS), along with astronomy's journals and data centers (a collaboration dubbed URANIA), has developed a distributed on-line digital library which has become the dominant means by which astronomers search, access and read their technical literature. Digital libraries such as the NASA Astrophysics Data System permit the easy accumulation of a new type of bibliometric measure, the number of electronic accesses (``reads'') of individual articles. We explore various aspects of this new measure. We examine the obsolescence function as measured by actual reads, and show that it can be well fit by the sum of four exponentials with very different time constants. We compare the obsolescence function as measured by readership with the obsolescence function as measured by citations. We find that the citation function is proportional to the sum of two of the components of the readership function. This proves that the normative theory of citation is true in the mean. We further examine in detail the similarities and differences between the citation rate, the readership rate and the total citations for individual articles, and discuss some of the causes. Using the number of reads as a bibliometric measure for individuals, we introduce the read-cite diagram to provide a two-dimensional view of an individual's scientific productivity. We develop a simple model to account for an individual's reads and cites and use it to show that the position of a person in the read-cite diagram is a function of age, innate productivity, and work history. We show the age biases of both reads and cites, and develop two new bibliometric measures which have substantially less age bias than citationsComment: ADS bibcode: 2005JASIS..56..111K This is the second paper (the first is Worldwide Use and Impact of the NASA Astrophysics Data System Digital Library) from the original article The NASA Astrophysics Data System: Sociology, Bibliometrics, and Impact, which went on-line in the summer of 200

Vintage capital growth theory: Three breakthroughs

Vintage capital growth models have been at the heart of growth theory in the 60s. This research line collapsed in the late 60s with the so-called embodiment controversy and the technical sophisitication of the vintage models. This paper analyzes the astonishing revival of this literature in the 90s. In particular, it outlines three methodological breakthroughs explaining this resurgence: a growth accounting revolution, taking advantage of the availability of new time series, an optimal control revolution allowing to safely study vintage capital optimal growth models, and a vintage human capital revolution, along with the rise of economic demography, accounting for the vintage structure of human capital similarly to physical capital age structuring. The related literature is surveyed.Vintage capital, embodied technical progress, growth accounting, optimal control, endogenous growth, vintage human capital, demography.

Optimal pattern of technology adoption under embodiment with a finite planning horizon : A multi-stage optimal control approach

By deriving the necessary conditions for a multi-stage discounted optimal control problem where the endogenous switching instants between regimes appear as an argument of the objective function and the state equation, we analyze the optimal pattern of technology adoption under embodiment with a finite planning horizon. The economy is characterized by the existence of an exogenously growing technology frontier and technology specific learning by doing. We obtain time varying durations for the adopted technologies to be in use due to finite planning horizon. We analyze numerically the effects of planing horizon, speed of learning, growth rate of technology and impatience rate on the optimal pattern.Multi-stage optimal control, technology adoption, learning by doing, embodiment

Vintage capital theory: Three breakthroughs

Vintage capital growth models have been at the heart of growth theory in the 60s. This research line collapsed in the late 60s with the so-called embodiment controversy and the technical sophisitication of the vintage models. This paper analyzes the astonishing revival of this literature in the 90s. In particular, it outlines three methodological breakthroughs explaining this resurgence: a growth accounting revolution, taking advantage of the availability of new time series, an optimal control revolution allowing to safely study vintage capital optimal growth models, and a vintage human capital revolution, along with the rise of economic demography, accounting for the vintage structure of human capital similarly to physical capital age structuring. The related literature is surveyed.Vintage capital; embodied technical progress; growth accounting; optimal control; endogenous growth; vintage human capital; demography.

Usage Bibliometrics

Scholarly usage data provides unique opportunities to address the known shortcomings of citation analysis. However, the collection, processing and analysis of usage data remains an area of active research. This article provides a review of the state-of-the-art in usage-based informetric, i.e. the use of usage data to study the scholarly process.Comment: Publisher's PDF (by permission). Publisher web site: books.infotoday.com/asist/arist44.shtm

Capital Tax Incidence: Fisherian Impressions from the Time Series

This paper accepts for the sake of argument the hypothesis that much of the time series correlation between tax and profit rates is spurious, and shows how nonetheless time series for profit rates, tax rates, and consumption can be organized, compared and interpreted using Fisher's (1930) theory of consumption in order to understand the incidence of capital taxes. Capital taxation is associated with a wedge between anticipated aggregate consumption growth and capital rental rates, suggesting that in one way or another capital owner behavior adjusts in the direction needed for some passing' of the capital tax. Conversely, most of the medium and low frequency deviations between anticipated aggregate consumption growth and capital rental rates are associated with capital taxation, as implied by aggregate time-separable Fisherian consumption theories in which time preference, non-tax capital market distortions, aggregation biases, and other determinants of aggregate consumption growth vary little over time.