Age, growth, and reproduction of permit (Trachinotus falcatus) in Florida waters

We examined 536 permit (Trachinotus falcatus, 65–916 mm FL) collected from the waters of Florida Keys and from the Tampa Bay area on Florida’s Gulf coast to describe their growth and reproduction.Among permit that we sexed, females ranged from 266 to 916 mm in length (mean=617) and males ranged from 274 to 855 mm (mean=601). Ages of 297 permit ranging from 102 to 900 mm FL were estimated from thin-sectioned otoliths (sagittae). The large proportion of otoliths with an annulus on the margin and an otolith from an OTC-injected fish suggested that a single annulus was formed each year during late spring or early summer.Permit reach a maximum age of at least 23 years.Permit grew rapidly until an age of about five years, and then growth slowed considerably. Male and female von Bertalanffy growth models were not significantly different, and the sexes-combined growth model was FL=753.1(1–e –0.348(Age+0.585)). Gonad development was seasonal, and spawning occurred during late spring and summer over artificial and natural reefs at depths of 10–30 m. Ovaries that contained oocytes in the final stages of oocyte maturation or postovulatory follicles were found during May–July. We estimated that 50% of the females in the population had reached sexual maturity by 547 mm and an age of 3.1 years and that 50% of the males in the population had reached sexual maturity by 486 mm and an age of 2.3 years. Because Florida regulations restrict the maximum size of permit caught in recreational and commercial fisheries to 20-inch (508-mm), most fish harvested are sexually immature. With the current size selectivity of the fishery, the spawning stock biomass of permit could decrease quickly in response to moderate levels of fishing mortality; thus, the regulations in place in Florida to restrict harvest levels appear to be justified.

Age, growth, mortality, and distribution of pinfish (Lagodon rhomboides) in Tampa Bay and adjacent Gulf of Mexico waters

Life-history dynamics of pinfish (Lagodon rhomboides) were examined from data derived from random station surveys conducted in Tampa Bay and adjacent Gulf of Mexico waters during 1993–97. In addition, patterns in spatial distribution and abundance in Gulf of Mexico waters were investigated. Ages determined from whole otoliths ranged from 0 to 7 years, and von Bertalanffy growth models for males and females were not significantly different. Von Bertalanffy growth model parameters were L∞=219.9 mm SL, k =0.33/yr, and t0 =–1.10 years for all fish combined. High gonadosomatic indices during October–December indicated that some spawning may occur in Tampa Bay. Estimated lengths at 50% maturity were 132 mm SL for males and 131 mm SL for females. Total instantaneous mortality rates derived from the Chapman-Robson estimator ranged from 0.88 to 1.08/yr, and natural mortality was estimated to be 0.78/yr. In Gulf of Mexico waters, pinfish catch rates declined with increasing depth, and most pinfish were caught in <17 m of water. Length distributions showed that pinfish segregate by size with increasing depth.

Hicks meets Hotelling: the direction of technical change in capital-resource economies

We analyze a two-sector growth model with directed technical change where man-made capital and exhaustible resources are essential for production. The relative profitability of factor-specific innovations endogenously determines whether technical progress will be capital- or resource-augmenting. We show that any balanced growth equilibrium features purely resource-augmenting technical change. This result is compatible with alternative specifications of preferences and innovation technologies, as it hinges on the interplay between productive efficiency in the final sector, and the Hotelling rule characterizing the efficient depletion path for the exhaustible resource. Our result provides sound micro-foundations for the broad class of models of exogenous/endogenous growth where resource-augmenting progress is required to sustain consumption in the long run, contradicting the view that these models are conceptually biased in favor of sustainability.

Finite-Sample Diagnostics for Multivariate Regressions with Applications to Linear Asset Pricing Models

In this paper, we propose several finite-sample specification tests for multivariate linear regressions (MLR) with applications to asset pricing models. We focus on departures from the assumption of i.i.d. errors assumption, at univariate and multivariate levels, with Gaussian and non-Gaussian (including Student t) errors. The univariate tests studied extend existing exact procedures by allowing for unspecified parameters in the error distributions (e.g., the degrees of freedom in the case of the Student t distribution). The multivariate tests are based on properly standardized multivariate residuals to ensure invariance to MLR coefficients and error covariances. We consider tests for serial correlation, tests for multivariate GARCH and sign-type tests against general dependencies and asymmetries. The procedures proposed provide exact versions of those applied in Shanken (1990) which consist in combining univariate specification tests. Specifically, we combine tests across equations using the MC test procedure to avoid Bonferroni-type bounds. Since non-Gaussian based tests are not pivotal, we apply the “maximized MC” (MMC) test method [Dufour (2002)], where the MC p-value for the tested hypothesis (which depends on nuisance parameters) is maximized (with respect to these nuisance parameters) to control the test’s significance level. The tests proposed are applied to an asset pricing model with observable risk-free rates, using monthly returns on New York Stock Exchange (NYSE) portfolios over five-year subperiods from 1926-1995. Our empirical results reveal the following. Whereas univariate exact tests indicate significant serial correlation, asymmetries and GARCH in some equations, such effects are much less prevalent once error cross-equation covariances are accounted for. In addition, significant departures from the i.i.d. hypothesis are less evident once we allow for non-Gaussian errors.

Exact Skewness-Kurtosis Tests for Multivariate Normality and Goodness-of-fit in Multivariate Regressions with Application to Asset Pricing Models

We study the problem of testing the error distribution in a multivariate linear regression (MLR) model. The tests are functions of appropriately standardized multivariate least squares residuals whose distribution is invariant to the unknown cross-equation error covariance matrix. Empirical multivariate skewness and kurtosis criteria are then compared to simulation-based estimate of their expected value under the hypothesized distribution. Special cases considered include testing multivariate normal, Student t; normal mixtures and stable error models. In the Gaussian case, finite-sample versions of the standard multivariate skewness and kurtosis tests are derived. To do this, we exploit simple, double and multi-stage Monte Carlo test methods. For non-Gaussian distribution families involving nuisance parameters, confidence sets are derived for the the nuisance parameters and the error distribution. The procedures considered are evaluated in a small simulation experi-ment. Finally, the tests are applied to an asset pricing model with observable risk-free rates, using monthly returns on New York Stock Exchange (NYSE) portfolios over five-year subperiods from 1926-1995.

Exact Multivariate Tests of Asset Pricing Models with Stable Asymmetric Distributions

In this paper, we propose exact inference procedures for asset pricing models that can be formulated in the framework of a multivariate linear regression (CAPM), allowing for stable error distributions. The normality assumption on the distribution of stock returns is usually rejected in empirical studies, due to excess kurtosis and asymmetry. To model such data, we propose a comprehensive statistical approach which allows for alternative - possibly asymmetric - heavy tailed distributions without the use of large-sample approximations. The methods suggested are based on Monte Carlo test techniques. Goodness-of-fit tests are formally incorporated to ensure that the error distributions considered are empirically sustainable, from which exact confidence sets for the unknown tail area and asymmetry parameters of the stable error distribution are derived. Tests for the efficiency of the market portfolio (zero intercepts) which explicitly allow for the presence of (unknown) nuisance parameter in the stable error distribution are derived. The methods proposed are applied to monthly returns on 12 portfolios of the New York Stock Exchange over the period 1926-1995 (5 year subperiods). We find that stable possibly skewed distributions provide statistically significant improvement in goodness-of-fit and lead to fewer rejections of the efficiency hypothesis.

Construcción de un instrumento para identificar el perfil de emprendedores bogotanos de la última década

El proyecto de investigación que se trabaja centra su atención en la siguiente cuestión: determinar un instrumento de recolección que permita identificar cuáles son las competencias que caracterizan a los emprendedores bogotanos creadores de empresas de rápido crecimiento. La presente es una investigación cualitativa que busca la mejor manera de preparar a los futuros emprendedores desde la educación superior. Si se conocen las competencias que acompañan al emprendedor se puede comprender mejor su capacidad de crear empresa y así buscar una mejor manera de preparar a los futuros emprendedores. Esto es importante para la economía de un país en general, máxime cuando se dan situaciones de depresión económica como el desempleo que se vive en la actualidad. “La creación y el desarrollo de nuevas empresas contribuye decisivamente a lograr el deseado bienestar para la sociedad, dado que permite incrementar el nivel de empleo, impulsar la innovación y mejorar la competitividad” (Acs, Audretch, & Braunerhjelm, 2006, pág. 83). La investigación abarca la búsqueda de competencias a nivel mundial basándose en estudios realizados por diferentes autores (Alles, Durán, Goleman, Shipmann, Varela, Boyatsis, Mc. Clelland y Blancero). El objetivo es desarrollar un instrumento que permita recolectar información de emprendedores bogotanos exitosos, con base en la clasificación de competencias que se realice a lo largo de la investigación.

Labor's shares - aggregate and industry: accounting for both in a model of unbalanced growth with induced innovation

The relative stability of aggregate labor's share constitutes one of the great macroeconomic ratios. However, relative stability at the aggregate level masks the unbalanced nature of industry labor's shares – the Kuznets stylized facts underlie those of Kaldor. We present a two-sector – one labor-only and the other using both capital and labor – model of unbalanced economic development with induced innovation that can rationalize these phenomena as well as several other empirical regularities of actual economies. Specifically, the model features (i) one sector ("goods" production) becoming increasingly capital-intensive over time; (ii) an increasing relative price and share in total output of the labor-only sector ("services"); and (iii) diverging sectoral labor's shares despite (iii) an aggregate labor's share that converges from above to a value between 0 and unity. Furthermore, the model (iv) supports either a neoclassical steadystate or long-run endogenous growth, giving it the potential to account for a wide range of real world development experiences.

Biomass partitioning and growth efficiency in four naturally regenerated forest tree species

Current forest growth models and yield tables are almost exclusively based on data from mature trees, reducing their applicability to young and developing stands. To address this gap, young European beech, sessile oak, Scots pine and Norway spruce trees approximately 0 to 10 years old were destructively sampled in a range of naturally regenerated forest stands in Central Europe. Diameter at base and height were first measured in situ for up to 175 individuals per species. Subsequently, the trees were excavated and dry biomass of foliage, branches, stems and roots was measured. Allometric relations were then used to calculate biomass allocation coefficients (BAC) and growth efficiency (GE) patterns in young trees. We found large differences in BAC and GE between broadleaves and conifers, but also between species within these categories. Both BAC and GE are strongly age-specific in young trees, their rapidly changing values reflecting different growth strategies in the earliest stages of growth. We show that linear relationships describing biomass allocation in older trees are not applicable in young trees. To accurately predict forest biomass and carbon stocks, forest growth models need to include species and age specific parameters of biomass allocation patterns.

Creativity and Growth in: Edmund Phelps (2013),Mass Flourishing. How Grassroots Innovation Created Jobs, Challenge and Change

This article reviews the thesis presented by Edmund Phelps, Mass Flourishing. How Grassroots Innovation Created Jobs, Challenge and Change (Princeton University Press, 2013) that modern economic growth is an indirect outcome of human creativity, and that the object of enlightened policy ought to be to promote this creativity, or flourishing, rather than economic growth per se. The book is a remarkable contribution to the literature on economic growth, with its focus on how entrepreneurship and innovation generates endogenous growth and, more importantly to the author, improves human satisfaction.

B2B e-commerce stages of growth; the strategic imperatives

Stages-of-growth has been the most popular approach used for strategy development and implementation. The major stages of growth models such as C. F. Gibson and R. F. Nolan (1974) have been widely discussed and are particularly useful in understanding the implementation of IS in organisations. These models might be more representative of e-commerce implementation, however, if they took into account more recent IS developments such as B2B e-commerce. Using a case study research undertaken in Australia, this study proposes a model of stages of growth based on the use of B2B e-commerce technologies and applications in Australian organisations. Four stages of growth proposed for B2B e-commerce implementation are (i) initial e-commerce; (ii) centralised e-commerce; (iii) looking inward for benefits; and (iv) global e-commerce.

Growth and condition in Australian fur seals Arctocephalus pusillus doriferus (Carnivora : Pinnipedia)

Mass and length growth models were determined for male (n = 69) and female (n = 163) Australian fur seals (Arctocephalus pusillus doriferus) collected at a breeding colony on Seal Rocks (38˚31′S, 145˚06′E), Bass Strait, in south-east Australia, between February and November during 1970–72. Growth was best described by the logistic model in males and the von Bertalanffy model in females. Asymptotic mass and length were 229 kg and 221 cm for males, and 85 kg and 163 cm for females. In all, 95% of asymptotic mass and length were attained by 11 years and 11 years, respectively, in males compared with 9 years and 5 years, respectively, in females. Males grew in length faster than females and experienced a growth spurt in mass coinciding with the onset of puberty (4–5 years). The onset of puberty in females occurs when approximately 86% of asymptotic length is attained. The rate of growth and sexual development in Australian fur seals is similar to (if not faster than) that in the conspecific Cape fur seal (A. p. pusillus), which inhabits the nutrient-rich Benguela current. This suggests that the low marine productivity of Bass Strait may not be cause of the slow rate of recovery of the Australian fur seal population following the severe over-exploitation of the commercial sealing era. Sternal blubber depth was positively correlated in adult animals with a body condition index derived from the residuals of the mass–length relationship (males: r² = 0.38, n = 19, P < 0.001; females: r² = 0.22, n = 92, P < 0.001), confirming the validity of using such indices on otariids. Sternal blubber depth varied significantly with season in adult animals. In males it was lowest in winter and increased during spring prior to the breeding season (r² = 0.39, n = 19, P < 0.03) whereas in females it was greatest during winter (r² = 0.05, n = 122, P< 0.05).

Simulating urban growth in a developing nation's region using a cellular automata-based model

Urbanization is one of the most evident global changes. Research in the field of urban growth modelling has generated models that explore for drivers and components of the urban growth dynamics. Cellular automata (CA) modeling is one of the recent advances, and a number of CA-based models of urban growth have produced satisfactory simulations of spatial urban expansion over time. Most application and test of CA-based models of urban growth which provide likely and reliable simulations has been developed in urban regions of developed nations; urban regions in the United States, in particular. This is because most of the models were developed in universities and research centers of developed nations, and these regions have the required data, which is extensive. Most of the population growth in the world, however, occurs in the developing world. While some European countries show signs of stabilization of their population, in less developed countries, such as India, population still grows exponentially. And this growth is normally uncoordinated, which results in serious environmental and social problems in urban areas. Therefore, the use of existing dynamic–spatial models of urban growth in regions of developing nations could be a means to assist planners and decision makers of these regions to understand and simulate the process of urban growth and test the results of different development strategies. The pattern of growth of urban regions of developing nations, however, seems to be different of the pattern of developed countries. The former use to be more dense and centralized, normally expanding outwards from consolidated urban areas; while the second is normally more fragmented and sparse. The present paper aims to investigate to how extent existing CA-based urban growth models tested in developed nations can also be applied to a developing country urban area. The urban growth model was applied to Porto Alegre City, Brazil. An expected contiguous expansion from existing urban areas has been obtained as following the historical trends of growth of the region. Moreover, the model was sensitive and able to portray different pattern of growth in the study area by changing the value of its parameters.

Foreign aid, leisure-effort choice, and economic growth

Using an endogenous growth model, this paper examines the growth and welfare effects of foreign aid in the recipient economy. The emphasis is on the incentive factor of the effort-leisure choice. Besides financing public services, part of the aid is transferred to the public. This increases individual wealth, thereby providing less incentives to individuals for human capital acquisition, but with more leisure. Thus, foreign aid may not always help the growth and welfare of the economy. Taking this incentive factor into account, we further study the issue on aid allocation in achieving the highest levels of growth and welfare. Along the balanced growth path, aid allocation for welfare maximization is different from that under growth maximization.

Pollution, health and economic growth

This paper examines the growth impacts of aid allocation on healthcare and pollution abatement in an endogenous growth model, and finds that the aid tied to them contributes positively to the equilibrium growth rate. Nonetheless, the growth rate can be reduced or even impaired if the ratio of aid on pollution abatement is lowered.