Underlying Growth Rate Research Articles

Comparative Transcriptomic Profiling of Brain and Liver in Phoenix Barbs (Spinibarbus denticulatus denticulatus) with Differential Growth Rates

Phoenix barb (Spinibarbus denticulatus denticulatus) is a notable fish species in South China and is valued for its ecological and economic importance. To elucidate the molecular basis underlying its growth, we collected transcriptome profiles from the brains and livers of individual fish with different growth rates and compared differentially expressed genes (DEGs) at 3 and 9 months after hatching (MAH). Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that the pathways associated with growth were predominantly enriched in fatty acid biosynthesis, AMPK signaling, PI3K-Akt signaling, estrogen signaling, and protein metabolism. Notably, a greater number of DEGs from the fast-growing group were associated with these pathways at the early growth stage (3 MAH) than at the later stage (9 MAH). Real-time quantitative PCR results further validated that the genes involved in these pathways exhibited higher expression levels in fast-growing samples. This study enhances our understanding of the genetic mechanisms underlying growth rate differences and provides valuable genetic resources for future growth-related molecular breeding programs of phoenix barbs.

Quantification of the time-varying epidemic growth rate and of the delays between symptom onset and presenting to healthcare for the mpox epidemic in the UK in 2022

The mpox epidemic in the UK began in May 2022, with rates of new cases unexpectedly and rapidly declining during August 2022. Interpreting trends in infection requires disentangling the underlying growth rate of cases from the delay from symptom onset to presenting to healthcare. We developed a nowcasting Bayesian method which incorporates time-varying delays (EpiLine) to quantify the changes in the delay from symptom onset to healthcare presentation and the underlying mpox growth rate over the period May-August 2022 in the UK. We show that the mean delay between symptom onset and healthcare presentation for mpox in the UK decreased from 22 days in early May 2022 to 10 days by early June and 8 days in August 2022. When we account for these dynamic delays, the time-varying growth rate declined gradually and continuously in the UK during the May-August 2022 period. Not accounting for varying time delays would have incorrectly characterised the growth rate by a sharp increase followed by a rapid decline in mpox cases. Our results highlight the importance of correctly quantifying the delay between symptom onset to healthcare presentation when characterising the epidemic growth of mpox in the UK. The gradual reduction in the rate of epidemic spread, which pre-dated the vaccine roll-out, is consistent with gradual risk reduction or acquired immunity amongst the highest risk individuals. Our study highlights the need for public health agencies to record the delays from symptom onset to healthcare presentation early in an outbreak.

Adaptive evolution shapes the present-day distribution of the thermal sensitivity of population growth rate.

Developing a thorough understanding of how ectotherm physiology adapts to different thermal environments is of crucial importance, especially in the face of global climate change. A key aspect of an organism's thermal performance curve (TPC)-the relationship between fitness-related trait performance and temperature-is its thermal sensitivity, i.e., the rate at which trait values increase with temperature within its typically experienced thermal range. For a given trait, the distribution of thermal sensitivities across species, often quantified as "activation energy" values, is typically right-skewed. Currently, the mechanisms that generate this distribution are unclear, with considerable debate about the role of thermodynamic constraints versus adaptive evolution. Here, using a phylogenetic comparative approach, we study the evolution of the thermal sensitivity of population growth rate across phytoplankton (Cyanobacteria and eukaryotic microalgae) and prokaryotes (bacteria and archaea), 2 microbial groups that play a major role in the global carbon cycle. We find that thermal sensitivity across these groups is moderately phylogenetically heritable, and that its distribution is shaped by repeated evolutionary convergence throughout its parameter space. More precisely, we detect bursts of adaptive evolution in thermal sensitivity, increasing the amount of overlap among its distributions in different clades. We obtain qualitatively similar results from evolutionary analyses of the thermal sensitivities of 2 physiological rates underlying growth rate: net photosynthesis and respiration of plants. Furthermore, we find that these episodes of evolutionary convergence are consistent with 2 opposing forces: decrease in thermal sensitivity due to environmental fluctuations and increase due to adaptation to stable environments. Overall, our results indicate that adaptation can lead to large and relatively rapid shifts in thermal sensitivity, especially in microbes for which rapid evolution can occur at short timescales. Thus, more attention needs to be paid to elucidating the implications of rapid evolution in organismal thermal sensitivity for ecosystem functioning.

Identification of genes showing differential expression profile associated with growth rate in skeletal muscle tissue of Landrace weanling pig.

Suppression subtractive hybridization was used to identify genes showing differential expression profile associated with growth rate in skeletal muscle tissue of Landrace weanling pig. Two subtracted cDNA populations were generated from musculus longissimus muscle tissues of selected pigs with extreme expected breeding values at the age of 100 kg. Three upregulated genes (EEF1A2, TSG101 and TTN) and six downregulated genes (ATP5B, ATP5C1, COQ3, HADHA, MYH1 and MYH7) in pig with genetic propensity for higher growth rate were identified by sequence analysis of 12 differentially expressed clones selected by differential screening following the generation of the subtracted cDNA population. Real-time PCR analysis confirmed difference in expression profiles of the identified genes in musculus longissimus muscle tissues between the two Landrace weanling pig groups with divergent genetic propensity for growth rate. Further, differential expression of the identified genes except for the TTN was validated by Western blot analysis. Additionally, the eight genes other than the ATP5C1 colocalized with the same chromosomal positions as QTLs that have been previously identified for growth rate traits. Finally, the changes of expression predicted from gene function suggested association of upregulation of expression of the EEF1A2, TSG101 and TTN genes and downregulation of the ATP5B, ATP5C1, COQ3, HADHA, MYH1 and MYH7 gene expression with increased growth rate. The identified genes will provide an important insight in understanding the molecular mechanism underlying growth rate in Landrace pig breed.

Food regime modulates physiological processes underlying size differentiation in juvenile intertidal mussels Mytilus galloprovincialis

Feeding and growth experiments were conducted to test the hypothesis that physiological attributes responsible for size differentiation among bivalves likely vary with environmental conditions. Juvenile mussels (Mytilus galloprovincialis) were collected from an intertidal population in Biscay, Spain (43°24′42,462″N02°56′43,659″W), in January 2007 and 2009. These mussels were maintained in the laboratory under either restrictive or optimal feeding conditions until fast- and slow-growing individuals on each maintenance regime could be identified. After fast- and slow-growing individuals were identified, the components of energy balance responsible for such growth rate differences were measured. The analysis of physiological traits indicates that under optimal food supply conditions, the capacity to ingest and absorb food and associated costs of growth are the main factors underlying growth rate differences. The set of physiological differences changed when size differentiation took place under restrictive food conditions. Higher rates of absorption coupled with reduced rates of metabolism accounted for faster growth in this case, especially under low food rations.

Metabolism correlates with variation in post‐natal growth rate among songbirds at three latitudes

Summary Variation in post‐natal growth rates is substantial among organisms and especially strong among latitudes because tropical and south temperate species typically have slower growth than north temperate relatives. Metabolic rate is thought to be a critical mechanism underlying growth rates after accounting for allometric effects of body mass. However, comparative tests on a large spatial scale are lacking, and the importance of metabolism for growth rates remains unclear both within and particularly across latitudes. Songbirds exhibit strong interspecific variation in growth rates across geographic space, although within latitudes an association between metabolic rate and growth rate has not always been observed. Moreover, the hypothesis that differences in growth rates across latitudes reflect underlying differences in metabolism is untested. Here, we investigate these possibilities across north temperate, south temperate and tropical study sites. Phylogenetic analyses showed that, for a given body mass, metabolic rates of north temperate nestlings were higher than tropical and south temperate species. Metabolic rates controlled for body mass correlated with post‐natal growth rates both within and among latitudes. Offspring body mass explained substantial residual variation in growth rates as expected under classic allometric theory. Our results suggest that variation in metabolic rates has an important influence on broad patterns of avian growth rates at a global scale. We suggest further studies that address the ecological and physiological costs and consequences of variation in metabolism and growth rates.

Business cycle, interest rate and money in the euro area: A common factor model

In this paper we model and analyze the contemporaneous correlation between interest rate, monetary aggregates, production and prices (of consumer goods, financial assets and real estate) of the euro area. To do this, firstly we estimate a common cyclical factor by means of an unobserved component model with the common factor located in variations in the underlying growth rates, that is, accelerations and decelerations of the variables. The variables mentioned share a significant cyclical factor being all procyclical except for narrow money. Finally we offer an explanation of this empirical finding based on the monetary policy strategy of interest rate pegging followed by the European Central Bank. In this regard, the shared cyclical information suggests (a) that inflation should be considered as a phenomenon that affects the whole economy, and therefore all prices, and (b) that monetary indicators such as monetary aggregates may contribute to the assessment of inflationary risks throughout the cycle.

Emergence of robust growth laws from optimal regulation of ribosome synthesis.

Bacteria must constantly adapt their growth to changes in nutrient availability; yet despite large-scale changes in protein expression associated with sensing, adaptation, and processing different environmental nutrients, simple growth laws connect the ribosome abundance and the growth rate. Here, we investigate the origin of these growth laws by analyzing the features of ribosomal regulation that coordinate proteome-wide expression changes with cell growth in a variety of nutrient conditions in the model organism Escherichia coli. We identify supply-driven feedforward activation of ribosomal protein synthesis as the key regulatory motif maximizing amino acid flux, and autonomously guiding a cell to achieve optimal growth in different environments. The growth laws emerge naturally from the robust regulatory strategy underlying growth rate control, irrespective of the details of the molecular implementation. The study highlights the interplay between phenomenological modeling and molecular mechanisms in uncovering fundamental operating constraints, with implications for endogenous and synthetic design of microorganisms.

Benefit–cost analysis of non-marginal climate and energy projects

Conventional benefit–cost analysis incorporates the normally reasonable assumption that the policy or project under examination is marginal. Among the assumptions this entails is that the policy or project is small, so the underlying growth rate of the economy does not change. However, this assumption may be inappropriate in some important circumstances, including in climate-change and energy policy. One example is global targets for carbon emissions, while another is a large renewable energy project in a small economy, such as a hydropower dam. This paper develops some theory on the evaluation of non-marginal projects, with empirical applications to climate change and energy. We examine the conditions under which evaluation of a non-marginal project using marginal methods may be wrong, and in our empirical examples we show that both qualitative and large quantitative errors are plausible.

IMPERFECT TRANSMISSION OF TECHNOLOGY SHOCKS AND THE BUSINESS CYCLE CONSEQUENCES

We investigate the business cycle effects of imperfect transmission of technology shocks within a basic real business cycle (RBC) model along two dimensions. First, we assume that agents cannot distinguish a temporary increase in productivity growth from a sustained increase in the underlying growth rate of productivity and instead must conduct signal extraction exercises and update beliefs about the source of aggregated shocks. Second, we propose a technology adjustment cost resulting in the slow diffusion of technological innovations into the production process. Both of these impediments to the transmission of technology result in a large initial wealth effect, increasing investment and hours less, relative to the usual RBC model without these frictions. Furthermore, each of these features is capable of producing a decline in hours on impact of the technology shock matching the negative response in hours found in the data by such works as Gali [American Economic Review89(1), 249–271 (1999)].

The evolutionary potential of Baker's weediness traits in the common morning glory, Ipomoea purpurea (Convolvulaceae)

Many reports have cited Baker's list of weediness traits, or those that exemplify the "ideal" weed, yet few have considered the evolutionary potential of such traits as a group. Thus, it is unknown whether constraints on the evolution of increased weediness, such as a lack of genetic variation or genetic correlations between the traits, are present. Ipomoea purpurea, the common morning glory, is a problematic weed that exhibits many of Baker's ideal weed traits. We used progeny from a half/full-sib breeding design in a series of three greenhouse experiments to assess the presence of genetic variation, narrow sense heritabilities, and genetic correlations in Baker's growth, competition, and fitness "weediness" traits in two populations of I. purpurea. We uncovered genetic variation underlying reproductive fitness traits and competitive ability in at least one population, but no evidence of genetic variation underlying growth rate in either population. Genetic correlations between many of the weediness characters differed significantly from zero; however, their direction and/or magnitude differed between populations. We found that increased weediness in the common morning glory is more likely to occur through selection on reproductive output and competitive ability rather than through selection on growth rate. Assessing Baker's traits in a quantitative genetics framework can provide a solid perspective on their evolutionary potential and a unique framework within which to determine how weeds will respond to different environmental stresses and/or scenarios of global climate change.

Density dependence and population dynamics of black rhinos (Diceros bicornis michaeli) in Kenya’s rhino sanctuaries

AbstractDensity‐dependent feedback mechanisms provide insights into the population dynamics and interactions of large herbivores with their ecosystem. Sex ratio also has particularly important implications for growth rates of many large mammal populations through its influence on reproductive potential. Therefore, the interrelationships between density‐dependent factors, comprising density, sex ratio and underlying growth rates (r) were examined for the Eastern black rhino (Diceros bicornis michaeli) living in three rhino sanctuaries in Kenya using four population models. The exponential and logistic models gave similar results and the former were accepted because they better portrayed the actual situation on the ground. Sex ratios in all sanctuary populations were positively correlated with r but interpreted with realization of other factors also affecting r. We caution that the results of population models should be interpreted alongside ground‐truthed observations. We recommend that future translocation strategies should take into account sex and age structures of the donor population, while future studies of density dependence should take into account both biotic and abiotic factors.

Impulsores del precio del petróleo a corto plazo: la integración energética de América del Sur

El objetivo de este documento es analizar cómo el comportamiento coyuntural y las condiciones estructurales del precio de la energía afectan la visión a corto y medio plazo del proceso de integración de la energía en Sudamérica (SA). Para este propósito, primero describimos la agenda energética mundial y el efecto de las oscilaciones actuales del precio del petróleo y el correspondiente ajuste del gas natural. A continuación, analizamos la perspectiva de las partes interesadas regionales acerca de la integración energética. Utilizamos dos enfoques metodológicos: primero calculamos los precios del petróleo según sus condiciones estructurales o fundamentales, segundo detectamos el modelo ARIMA correcto con valores atípicos y efectos de calendario para el precio del petróleo West Texas Intermediate (WTI) y el precio del gas natural Henry Hub (HH). Con esta información desarrollamos una propuesta de análisis basada en su tasa de crecimiento subyacente e inercia.

Testing the DMAA's Recommendations for Disease Management Program Evaluation

The objective of this study was to compare and contrast findings regarding the financial savings projections of the disease management (DM) programs of 2 large employers based on different evaluation methods. In particular, this research tests the impact of differences in assumptions on the underlying growth rate of group health costs, exclusions of high-cost conditions and claims, and the length of the baseline period for determined health care costs. A pre-post study design was used. The data for this research came from 2 large employers in the consumer goods industry with comprehensive Health and Productivity Management programs. It contained medical and prescription drug claims and health plan enrollment data as well as program activity data from 2001 to 2005, covering an average yearly sample size of 201,037 members with 12 consecutive months of enrollment. Analyses were done on group-level averages using nominal cost data and were run to reflect the impact of a DM-only intervention. While the trend estimate and length of baseline had the largest effects on estimated program impact, the use of exclusions had an important effect as well. These findings demonstrate the importance of developing and instituting a standardized evaluation methodology. Without increasing consistency in the way evaluators develop their methodologies, it will remain difficult to be able to compare one evaluation to another, or to have faith in the results at hand.

Is growth a reliable indicator of habitat quality and essential fish habitat for a juvenile estuarine fish?

A common assumption throughout the marine ecological and fisheries literature is that growth is a valid indicator of habitat quality and can be used as a criterion for designation of essential fish habitat (EFH). In this study, the validity of growth as an index of habitat quality was tested by examining how variability in otolith growth was related to abiotic and biotic environmental conditions and could be biased by previous growth history, density dependence, and selective mortality. The study was conducted with juvenile Atlantic croaker (Micropogonias undulatus) collected in two North Carolina, USA, estuaries during two seasons of two recruitment years. Water temperature, a component of habitat quality, explained nearly 40% of the variability in juvenile otolith growth. There was also evidence that estimates of growth could be biased by density dependence (slower growth at higher conspecific abundance) and by selective mortality (higher mortality of individuals with relatively slower larval and juvenile otolith growth). Studies using growth-based assessment of habitat quality that fail to identify factors underlying growth rate differences among habitats may reach incorrect decisions regarding quality of different habitats and assignment of EFH.

On Non-Marginal Cost-Benefit Analysis

Conventional cost-benefit analysis incorporates the normally reasonable assumption that the policy or project under examination is marginal in the sense that it will not significantly change relative prices. In particular, it is assumed that the policy or project does not change the underlying growth rate of the economy. However, these assumptions may be inappropriate in some important circumstances, such as large development projects in small economies, or large-scale infrastructure investment programmes. This paper develops the theory on the evaluation of non-marginal policies and projects, with an empirical application to the mitigation of global climate change. We examine the conditions under which evaluation of a non-marginal project using marginal methods may be both qualitatively and quantitatively wrong, and explore the magnitude of the potential error using a commonly employed integrated assessment model of climate change.

Tracking the new economy: Using growth theory to detect changes in trend productivity

The acceleration of productivity after 1995 prompted a debate over whether the economy's underlying growth rate would remain high. In this paper, we draw on growth theory to identify variables other than productivity—namely consumption and labor compensation—to help estimate trend productivity growth. We treat that trend as a common factor with two “regimes,” high- and low-growth. Our analysis picks up striking evidence of a return in 1997 to the high-growth regime, nearly 25 years after a switch from high- to low-growth. We find that both the common factor and regime-switching aspects of the model are important for identifying changes in trend productivity, and also show that the trend breaks are more difficult to detect with per capita (as opposed to per hour) based data because of persistent labor supply shifts. Finally, we argue that our methodology is effective in detecting changes in trend in real time: In the case of the 1990s, the methodology would have signaled the regime switch by 1999, or within roughly six quarters of when it occurred according to the full sample.

Tracking the New Economy: Using Growth Theory to Detect Changes in Trend Productivity

The acceleration of productivity since 1995 has prompted a debate over whether the economy's underlying growth rate will remain high. In this paper, we propose a methodology for estimating trend growth that draws on growth theory to identify variables other than productivity - namely consumption and labor compensation - to help estimate trend productivity growth. We treat that trend as a common factor with two regimes high-growth and low-growth. Our analysis picks up striking evidence of a switch in the mid-1990s to a higher long-term growth regime, as well as a switch in the early 1970s in the other direction. In addition, we find that productivity data alone provide insufficient evidence of regime changes; corroborating evidence from other data is crucial in identifying changes in trend growth. We also argue that our methodology would be effective in detecting changes in trend in real time: In the case of the 1990s, the methodology would have detected the regime switch within two years of its actual occurrence according to subsequent data.

Seasonality and Markov switching in an unobserved component time series model

It is generally acknowledged that the growth rate of output, the seasonal pattern, and the business cycle are best estimated simultaneously. To achieve this, we develop an unobserved component time series model for seasonally unadjusted US GDP. Our model incorporates a Markov switching regime to produce periods of expansion and recession, both of which are characterized by different underlying growth rates. Although both growth rates are time-varying, they are assumed to be cointegrated. The analysis is Bayesian, which fully accounts for all sources of uncertainty. Comparison with results from a similar model for seasonally adjusted data indicates that the seasonal adjustment of the data significantly alters several aspects of the full model.

The euro: The logic and inevitability of UK adoption

A competitive, smoothly functioning financial system is widely accepted as a prerequisite for realising an economy's growth potential. Modern growth theories have broadened their focus beyond the rate of interest as the means of equilibrating savings and investment to the contribution that efficiently operating financial markets make to underlying growth rates. The successful introduction of the euro marks an historic and significant step towards the achievement of a competitive, smoothly functioning pan-European integrated financial system. The elimination nominal currency risk for participants and reduced transaction costs are only the start of a continuing dynamic process that is steadily reducing asymmetries and increasing contestability. More generally a single currency and a smoothly functioning pan-European financial system are necessary counterparts to a single EU market in goods, services, labour and financial capital. This paper advances the argument that the integration of the EU's financial markets should be viewed as part of a longer-term process of economic and political integration in Europe. The UK is unable to stop this trend and UK business in general, and the UK financial markets in particular, would be wise to acknowledge these forces and to start to work with them. Marketing UK financial services with a view to UK membership of EMU would not only align marketing with the flow of history, but also it offers the prospects of a greater longer-term return.