Long-term Growth Rate Research Articles

Environment-to-phenotype mapping and adaptation strategies in varying environments

Biological organisms exhibit diverse strategies for adapting to varying environments. For example, a population of organisms may express the same phenotype in all environments ("unvarying strategy") or follow environmental cues and express alternative phenotypes to match the environment ("tracking strategy"), or diversify into coexisting phenotypes to cope with environmental uncertainty ("bet-hedging strategy"). We introduce a general framework for studying how organisms respond to environmental variations, which models an adaptation strategy by an abstract mapping from environmental cues to phenotypic traits. Depending on the accuracy of environmental cues and the strength of natural selection, we find different adaptation strategies represented by mappings that maximize the long-term growth rate of a population. The previously studied strategies emerge as special cases of our model: The tracking strategy is favorable when environmental cues are accurate, whereas when cues are noisy, organisms can either use an unvarying strategy or, remarkably, use the uninformative cue as a source of randomness to bet hedge. Our model of the environment-to-phenotype mapping is based on a network with hidden units; the performance of the strategies is shown to rely on having a high-dimensional internal representation, which can even be random.

Establishing a cryopreservation protocol for patient-derived xenografts of prostate cancer.

Serially transplantable patient-derived xenografts (PDXs) are invaluable preclinical models for studying tumor biology and evaluating therapeutic agents. As these models are challenging to establish from prostate cancer specimens, the ability to preserve them through cryopreservation has several advantages for ongoing research. Despite this, there is still uncertainty about the ability to cryopreserve PDXs of prostate cancer. This study compared three different cryopreservation protocols to identify a method that can be used to reproducibly cryopreserve a diverse cohort of prostate cancer PDX models. One serially transplantable prostate cancer PDX from the Melbourne Urological Research Alliance cohort was used to compare three cryopreservation protocols: slow freezing in fetal calf serum (FCS) with 10% dimethyl sulfoxide (DMSO), FCS with 10% DMSO supplemented with the Rho-associated kinase (ROCK) inhibitor Y-27632 and vitrification. The efficiency of the slow freezing protocols was then assessed in 17 additional prostate cancer PDXs. Following cryopreservation, PDXs were re-established in host mice that were either intact and supplemented with testosterone or castrated. Graft take rate, tumor growth, histological features, and transcriptome profiles before and after cryopreservation were compared. Slow freezing maintained the viability and histological features of prostate cancer PDXs, and the addition of a ROCK inhibitor increased their growth following cryopreservation. Using the slow freezing method, we re-established 100% of PDXs grown in either testosterone-supplemented or castrated host mice. Importantly, the long-term tumor growth rate and transcriptome profile were maintained following cryopreservation. This study has identified a protocol to reliably cryopreserve and re-establish a diverse cohort of serially transplantable PDXs of prostate cancer. This study has the potential to significantly improve the practicality of maintaining PDX models. Cryopreservation may also increase the accessibility of these important resources and provide new opportunities for preclinical studies on a broader spectrum of prostate tumors.

Neo-liberal Macroeconomic Policy and Structural Transformation of Indian Economy: Impact on Income, Employment and Distribution

Predominant objective of macroeconomic policies in developing countries has been to achieve higher level of potential economic growth and sustain it once it is achieved. Macroeconomic policy in India, on the backdrop of severe balance of payment crisis, has witnessed major shift in the early 1990s when neo-liberal economic policy on the pressure of IMF and World Bank has been adopted abandoning the socialist pattern of economic policy pursued in the post-independence period. Since implementation its scope has been consistently widening in terms of economic reform in different sectors of the economy, now its impact both positive and adverse is clearly visible. Since the last two and half decades, the serious adverse implication of the new economic policy is visible, particularly on the widening income inequality, although there has been positive effect on achieved higher aggregate economic growth. The major channel through which it is manifested is less than desired performance on labour market as employment generation has slowed down drastically when compared to the long-term trend in employment generation. In post-1991 period during 1993–1994 and 2011–2012, the growth in employment has been around 1.3% per annum against long-term growth rate of 2.11% per annum between 1977–1978 and 2011–2012. Even those employments generated are mostly in construction and low-productive services sector and are precarious and casual in nature. The paper has contributed in understanding the phenomena of rising inequality in the nature of production, through examination of structure and composition of output, employment and emerging wide disparity across sectors. We have shown by examining output per worker and concentration of workforce across sectors the problem of existing and rising income inequality.

Sex-Specific Predation Patterns on Kudu and Impala

Long-term growth rates of ungulate populations can be affected where disproportionate mortality occurs to adult females through predation. To investigate differences between lions (Panthera leo) and wild dogs (Lycaon pictus) in relative selection for female prey, we analysed ranger records for impala (Aepyceros melampus) and kudu (Strepsiceros zambesiensis) from Madikwe and Pilanesberg Nature reserves, South Africa. Each kill was categorized by sex of killed animal (female, male), likely predator (lion, wild dog) and season of kill (early wet, late wet, early dry, late dry). Our findings at Madikwe and Pilanesberg show that wild dog kill data for both kudu and impala are female-biased whereas lion kill data for the two ungulate species are male-biased.

Mapping the Technological Frontier

Are there technologies that make firms that produce them and places where they are created thrive? What are the features that make these technologies impactful? This article seeks to understand where is that the value of technologies reside, to understand which are the features that make them virtuous and impactful. Using patent data, it proposes a way of identifying impactful technologies based on three distinctive characteristics, the rate at which a technology improves, the variety of other type of technologies that complement with it, and the pervasiveness of its use. These measures are then used to draw a technological frontier. It is shown that firms and economic sectors with a higher share (or number) of these frontier technologies are related to higher operating revenues, while countries with a higher share (or number) tend to have higher long-term growth rates. To prove the latter a new database was collected, which geo-locates patents granted to foreigners by the United States patent office from 1836 to 1975.

Bitcoin Spreads Like a Virus

In this paper we provide a mathematical derivation that links traditional time-value-of-money concepts to Metcalfe value, and use Bitcoin, Facebook as numerical examples of the proof. There is compelling evidence that suggests that the growth and price of bitcoin and other cryptocurrencies are likely to proceed according to a relatively straightforward mathematical model similar to the growth curves of Facebook and other networks. Using observed data for Bitcoin, we derive the relationships between price, number of users, and time, and show that the resulting market prices likely follow a Gompertz sigmoid growth function. This function, historically used to describe the growth of biological organisms like bacteria, tumors, and viruses, likely has some application to network economics. We conclude that the long-term growth rate in users has considerable effect on the long-term price of bitcoin.

The measurement of atmospheric CO2 at KMA GAW regional stations, its characteristics, and comparisons with other East Asian sites

Abstract. To understand the carbon cycle at policy-relevant spatial scales, a high density of high-quality CO2 measurement sites is needed. In 2012, the Korea Meteorological Administration (KMA) installed CO2 monitoring systems at Anmyeondo (AMY) in the west, Jejudo Gosan Suwolbong (JGS) in the southwest, and Ulleungdo (ULD) in the east of South Korea. Three stations were instrumented with identical greenhouse gas measurement systems based on cavity ring-down spectroscopy (CRDS) and a new drying system developed by KMA and the Korea Research Institute of Standards and Science (KRISS). This drying system is suitable in humid areas; water vapor measured using CRDS in ambient air was 0.001 % to 0.004 % across the stations. Measurement uncertainties expressed by the quadrature sum of the uncertainties from the drying system, scale propagations, repeatability, and reproducibility were ∼0.11 ppm from all KMA stations in the 68 % confidence interval. Average monthly CO2 enhancements above the local background at each station were 4.3±3.3 ppm at AMY, 1.7±1.3 ppm at JGS, and 1±1.9 ppm (1σ) at ULD, respectively, during 2012 to 2016. At AMY station, located between China and South Korea, CO2 annual means and seasonal variations are also greater than the other KMA stations, indicating that it is affected not only by local vegetation, but also added anthropogenic sources. Selected baseline CO2 at AMY and at JGS in the west of South Korea is more sensitive to East Asia (e.g., China) according to wind direction and speed. Through the comparison of long-term trends and growth rates at AMY with other East Asian stations over 15 years, it was suggested that they could be affected not only by local vegetation but also by measurement quality.

A Mathematical Analysis of Technical Analysis

ABSTRACTIn this paper, we investigate trading strategies based on exponential moving averages (ExpMAs) of an underlying risky asset. We study both logarithmic utility maximization and long-term growth rate maximization problems and find closed-form solutions when the drift of the underlying is modelled by either an Ornstein-Uhlenbeck process or a two-state continuous-time Markov chain. For the case of an Ornstein-Uhlenbeck drift, we carry out several Monte Carlo experiments in order to investigate how the performance of optimal ExpMA strategies is affected by variations in model parameters and by transaction costs.

Modeling Population Dynamics of Kochia (Bassia scoparia) in Response to Diverse Weed Control Options

AbstractKochia [Bassia scoparia(L.) A. J. Scott] is a problematic weed species across the Great Plains, as it is spreading fast and has developed herbicide-resistant biotypes. It is imperative to understand key life-history stages that promote population expansion ofB. scopariaand control strategies that would provide effective control of these key stages, thereby reducing population growth. Diversifying weed control strategies has been widely recommended for the management of herbicide-resistant weeds. Therefore, the objectives of this study were to develop a simulation model to assess the population dynamics ofB. scopariaand to evaluate the effectiveness of diverse weed control strategies on long-term growth rates ofB. scopariapopulations. The model assumed the existence of a glyphosate-resistant (GR) biotype in theB. scopariapopulation, but at a very low proportion in a crop rotation that included glyphosate-tolerant corn (Zea maysL.) and soybean [Glycine max(L.) Merr.]. The parameter estimates used in the model were obtained from various ecological and management studies onB. scoparia. Model simulations indicated that seedling recruitment and survival to seed production were more important than seedbank persistence forB. scopariapopulation growth rate. Results showed that a diversified management program, including glyphosate, could provide excellent control ofB. scopariapopulations and potentially eliminate already evolved GRB. scopariabiotypes within a given location. The most successful scenario was a diverse control strategy that included one or two preplant tillage operations followed by preplant or PRE application of herbicides with residual activities and POST application of glyphosate; this strategy reduced seedling recruitment, survival, and seed production during the growing season, with tremendous negative impacts on long-term population growth and resistance risk inB. scoparia.

Political instability and economic growth in Africa

Political instability, especially when it is of a violent nature, diminishes the productive, as well as the transactional capacities of the economy. This has adverse consequences for investment and thus future economic growth, a situation which in turn creates a fragile socio-political environment. The relationship between political instability and economic growth flows in either direction; political instability resulting in low economic growth (PI → LEG) and low economic growth resulting in political instability (LEG → PI). From the PI → LEG point of view, political instability influences the latter through a number of channels including the tax system, government spending and fiscal deficit, and inflation, all of which affect the level of investment, and thus influence future economic growth rates. From the LEG → PI point of view, low economic growth rates create conditions favourable for political instability. Reviewing economic and political stability data from 52 African countries for the period 1980 to 2013, the analysis demonstrates through some scenarios that higher and relatively more stable long-term (1980–2013) average growth rates correlate with lower levels of political instability in most of the pairwise comparisons of the countries. This is shown to be especially true for less resource-dependent countries. Empirical analyses of the data comprising all the countries under investigation find there to be a strong bi-directional direct relationship between political stability and the level of growth, and it is even more so the case for conflict-affected countries, unlike the non-conflict-affected countries. Further analyses using three-year averages of the data from 1981 to 2013 find that greater fluctuations in the growth rate adversely affect the level of political stability in especially conflict-affected countries, thus indicating a correlation between economic instability and political instability.

The long-term relationship between emissions and economic growth for SO2, CO2, and BC

Simplified assumptions regarding the relationship between per capita income and emissions are oftentimes utilized to generate future emission scenarios in integrated assessment models (IAMs). One such relationship is an environmental Kuznets curve (EKC), where emissions first increase, then decline with income growth. However, current knowledge about this relationship lacks the specificity needed for each sector and pollutant pairing, which is important for future emission scenarios. To fill this knowledge gap, we analyze the historical relationship between per capita income and emissions of SO2, CO2, and black carbon (BC) utilizing widely-used global, country-level emission inventories for the following four sectors: power, industry, residential, and transportation. Based on a modeling setup using long-term growth rates, emissions of SO2 from the power and industrial sectors, as well as CO2 from the industrial and the residential sectors, largely follow an EKC pattern. Income-emission trajectories for SO2 and CO2 from other sectors, and those for BC from all sectors, do not show an EKC, however. Results across different global inventories were variable, indicating that uncertainties within historical emission trajectories persist. Nonetheless, these results demonstrate that long-term income-emission trajectories of air pollutants are both sector and pollutant specific. Future reference trajectories of SO2 and BC from three IAMs show earlier estimates of turnover incomes and faster rates of emission declines when compared to historical data. Users of future emission scenarios derived using EKC assumptions should consider the underlying uncertainties in such projections in light of this historical analysis.

Financial Sector Bargaining Power, Aggregate Growth and Systemic Risk

During the last three decades Western economies have been characterized by an increasing role played by the financial sector. This process, called financialization, has been associated with lower economic growth, increased inequality and declining financial stability. In this article I develop a simple framework to study the effects of financialization on aggregate growth and systemic risk. The main driver of this mechanism is the bargaining power of intermediaries. Indeed, financial institutions, by absorbing a larger quota of income from their borrowers, can reduce the incentive for new entrepreneurs to enter in the market. Because of that, both the long-term potential growth rate and the overall stability of the system can be negatively affected by an overdeveloped financial sector.

Can enzymatic stoichiometry be used to determine growth-limiting nutrients for microorganisms? - A critical assessment in two subtropical soils

The measurement of potential enzymatic activities has been proposed as an efficient method to infer nutrient limitations for microorganisms in environmental samples. To validate this use, confirmation with direct methods of microbial growth responses to resource additions are required. We experimentally manipulated nutrient-poor soils from the afromontane subtropics with relatively low (grassland soils, ca. 4% soil carbon (C)) or high organic matter content (forest soils, ca. 13% soil C) with nutrient additions (plant material added at 8 mg C g−1 soil combined with mineral N and/or P to reach C:N:P mass-ratios of 10:1:1) in a multifactorial design for one month in order to shift the microbial community towards C-, N- or P-limitation. We then measured the responses of the most commonly measured indicator enzymes used to infer growth limiting nutrients, using ß-1,4-glucosidase, ß-1,4-N-acetylglucosaminidase and leucine aminopeptidase, and acid phosphatase as indicators for C-, N- and P-acquiring enzymatic activities, respectively. In the same soil samples, we also determined the responses in bacterial (3H-leucine incorporation) and fungal growth rates (14C-acetate incorporation into ergosterol) to nutrient supplements, and also verified these with biomass responses (microbial PLFA and ergosterol concentrations) to the factorial nutrient loading amendments. Ratios of C-, N-, and P-acquiring enzymes indicated that the grassland soils were primarily P-limited, and secondarily co-limited by C and N, while the forest soils were co-limited by C and P. However, short-term responses in growth rates and respiration to nutrient additions, along with long-term growth rate, respiration and biomass responses to nutrient loading treatments all indicated that bacterial growth, fungal growth and respiration were primarily limited by C in both grassland and forest soils. We conclude that enzymatic ratios do not capture the growth-limiting factors for bacterial growth, fungal growth, or respiration in soil. Furthermore, the addition of C-rich plant material could shift the fungal community into N-limitation, while bacteria were shifted into co-limitation by both C and N, revealing that bacteria and fungi can be limited by different nutrients within the same soil environment.

Russian budget structure efficiency: Empirical study

This paper investigates the economic efficiency of Russian public expenditures in 2002–2016 by estimation of their multiplicative impact on the GDP level and economic growth. We use the empirical methodology based on Corsetti et al. (2012). We estimate a number of fiscal multipliers: on national security, law-enforcement activity, national defense, education, health care and sport and road infrastructure. For assessing the influence of budget structure on long-term economic growth rates, we estimate the SVAR model in which GDP growth is a structural variable. The research shows a positive influence of budgetary resources redistribution from non-productive government expenditures to productive ones on economic development.

Was higher education a major channel through which the US became an economic superpower in the 20th century?

This paper offers a thesis for why the US overtook the UK and other European countries in the 20th century in both aggregate and per capita GDP as a case study of recent models of endogenous growth, where ‘human capital’ is the engine of growth. By human capital we mean an intangible asset, best thought of as a stock of embodied and disembodied knowledge comprising education, information, entrepreneurship, and productive and innovative skills, which is formed through investments in schooling, job training, and health as well as through research and development projects and informal knowledge transfers (cf. Ehrlich and Murphy 2007). The conjecture is that the ascendancy of the US as an economic superpower in the 20th century owes considerably to its faster human capital formation relative to that of the UK and ‘old Europe.’ This paper assesses whether the thesis has legs to stand on through both stylized facts and a supplementary quasi-experimental empirical analysis. The stylized facts indicate that the US led other major developed countries in schooling attainments per adult population member, beginning in the latter part of the 19th century and lasting throughout the 20th century, especially at the secondary and tertiary levels. The quasi-experimental analysis constitutes the first attempt to test the hypothesis that the US’s ascendancy to a major economic power stems largely from the impact of the first Morrill Act of 1862, which launched the public higher education movement in the US through the establishment of land grant colleges and universities across the nation during the latter part of the 19th century. The higher education movement appears to have spearheaded a higher long-term rate of growth in per capita income in the US relative to the UK and other major European countries.

Projecting Pharmaceutical Expenditure in EU5 to 2021: Adjusting for the Impact of Discounts and Rebates.

BackgroundWithin (European) healthcare systems, the predominant goal for pharmaceutical expenditure is cost containment. This is due to a general belief among healthcare policy makers that pharmaceutical expenditure—driven by high prices—will be unsustainable unless further reforms are enacted.ObjectiveThe aim of this paper is to provide more realistic expectations of pharmaceutical expenditure for all key stakeholder groups by estimating pharmaceutical expenditure at ‘net’ prices. We also aim to estimate any gaps developing between list and net pharmaceutical expenditure for the EU5 countries (i.e. France, Germany, Italy, Spain, and the UK).MethodsWe adjusted an established forecast of pharmaceutical expenditure for the EU5 countries, from 2017 to 2021, by reflecting discounts and rebates not previously considered, i.e. we moved from ‘list’ to ‘net’ prices, as far as data were available.ResultsWe found an increasing divergence between expenditure measured at list and net prices. When the forecasts for the five countries were aggregated, the EU5 (unweighted) average historical growth (2010–2016) rate fell from 3.4% compound annual growth rate at list to 2.5% at net. For the forecast, the net growth rate was estimated at 1.5 versus 2.9% at list.ConclusionsOur results suggest that future growth in pharmaceutical expenditure in Europe is likely to be (1) lower than previously understood from forecasts based on list prices and (2) below predicted healthcare expenditure growth in Europe and in line with long-term economic growth rates. For policy makers concerned about the sustainability of pharmaceutical expenditure, this study may provide some comfort, in that the perceived problem is not as large as expected.

Environmental policy and human capital inequality: A matter of life and death

This paper analyzes the economic implications of an environmental policy when we account for the life expectancy of heterogeneous agents. In a framework in which everyone suffers from pollution but health status also depends on individual human capital, we find that the economy may be stuck in a trap in which inequality rises steadily, especially when the initial pollution intensity of production is too high. We emphasize that such inequality is in the long run costly for the economy in terms of health and growth. Therefore, we study whether a tax on pollution associated with an investment in pollution abatement can be used to address this situation. We show that a stricter environmental policy may allow the economy to escape from the inequality trap while enhancing the long-term growth rate when the initial inequality in human capital is not too large.

Does infrastructure have a transitory or longer-term impact? Evidence from China

It is ambiguous in the literature whether infrastructure only has transitory effects by lifting the level of aggregate output, or a longer-term impact by boosting the growth rate of output. The paper attempts to shed empirical light on this issue by looking at the case of China. It employs an infrastructure-augmented production function framework and a growth regression model, and adopts panel threshold regressions to address non-linearity. The results show that infrastructure stocks (except railways) are more productive than other physical capital in raising output levels, but not so when it comes to the effect on long-term growth rates. The analysis also finds that infrastructure's productivity depends on whether it is oversupplied or in shortage relative to non-infrastructure capital.

ENVIRONMENTAL POLICY AND GROWTH WHEN ENVIRONMENTAL AWARENESS IS ENDOGENOUS

This paper examines the relationship between environmental policy and growth when green preferences are endogenously determined by education and pollution. We consider an environmental policy in which the government implements a tax on pollution and recycles the revenue to fund pollution abatement activities and/or an education subsidy (influencing green behaviors). When the sensitivity of agents' environmental preferences to pollution and human capital is high, the economy can converge to a balanced growth path equilibrium with damped oscillations. We show that this environmental policy can both remove the oscillations, associated with intergenerational inequalities, and enhance the long-term growth rate. However, this solution requires that the revenue from the tax rate must be allocated to education and direct environmental protection simultaneously. We demonstrate that this type of mixed-instrument environment policy is an effective way to address environmental and economic issues in both the short and the long run.

How Synergy Effects of Paid and Digital Owned Media Influence Brand Sales

ABSTRACT Research is ongoing about how investment in paid media and digital owned media drives changes in brand sales. The advertising-intensive curve (Jones, 1990) suggests that paid-media investment is correlated to brands9 market position in the repeat-purchase packaged-product category. Building on that framework, the authors analyzed 838 brands in 14 product and service categories for share of spend in paid media and share of digital owned media—unique visitor traffic and traffic to social media—taking into account their relationship with share of sales. Investment in digital owned media was correlated to brands9 long-term sales growth rates and to the balance between paid-media and owned-media investment.