Infrastructure and economic growth in East Asia

This paper examines whether infrastructure investment has contributed to East Asia's economic growth using both a growth accounting framework and cross-country regressions. For most of the variables used, both the growth accounting exercise and cross-country regressions fail to find a significant link between infrastructure, productivity and growth. These conclusions contrast strongly with previous studies finding positive and significant effect for all infrastructure variables in the context of a production function study. This leads us to conclude that results from studies using macro-level data should be considered with extreme caution. The Authors suggest that infrastructure investment may have had the primary function of relieving constraints and bottlenecks as they arose, as opposed to directly encouraging growth.Transport Economics Policy&Planning,Banks&Banking Reform,Achieving Shared Growth,Economic Theory&Research,Non Bank Financial Institutions

Infrastructure and economic growth in the Middle East and North Africa

This paper analyzes the impact of infrastructure on growth of total factor productivity and per capita income, using both growth accounting techniques and cross-country growth regressions. The two econometric techniques yield some consistent and some different results. Regressions based in the growth accounting framework suggest that electricity production helps explain cross-country differences in total factor productivity growth in the Middle East and North Africa region. Growth regressions support that conclusion, while also stressing an effect of telecommunications infrastructure. Finally, growth regressions also indicate quite consistently that the returns to infrastructure have been lower in the Middle East and North Africa region than in developing countries as a whole.Transport Economics Policy&Planning,Achieving Shared Growth,Economic Growth,E-Business,Energy Production and Transportation

Regional Convergence and Aggregate Growth

A striking feature of US states convergence is the link between the spatial speed of convergence and the aggregate growth rate: fast aggregate growth induces a reduction in regional inequalities. This paper uses a neoclassical growth framework with integrated economies in order to capture this phenomena. As it has been stressed by Ventura (1997), the interdependence between regional economies through the access to common markets generates a link between aggregate evolution and spatial convergence dynamics. The paper has two mains results. First, we show how deep parameters of the economy determines quantitatively the magnitude of this link. Second, we propose two directions for testing the model and we provide some empirical evidence using US states data on personal income. These results are mixed, only a part of the convergence pattern is well captured by the model.

Solution of Low-Thrust Lambert Problem with Perturbative Expansions of Equinoctial Elements

A method for solving the so-called low-thrust Lambert problem is proposed. After formulating it as a two-point boundary value problem, where initial and final positions are provided in terms of equinoctial variables, a first-order perturbative approach is used for investigating the variation of orbital elements generated by the low-thrust propulsion system, which acts as a perturbing parameter with respect to the zero-order Keplerian motion. An implicit algebraic problem is obtained, which allows for the determination of the low-thrust transfer trajectory that drives the equinoctial parameters from the initial to the final values in a prescribed time. Three test cases are presented, which demonstrate the flexibility of the method for different mission scenarios: an interplanetary transfer from Earth to Mars, a spiral multirevolution transfer from low Earth orbit to the International Space Station, and a maneuver to a highly elliptical orbit with large plane change

Embryonic, Larval, and Juvenile Development of the Sea Biscuit Clypeaster subdepressus (Echinodermata: Clypeasteroida)

Sea biscuits and sand dollars diverged from other irregular echinoids approximately 55 million years ago and rapidly dispersed to oceans worldwide. A series of morphological changes were associated with the occupation of sand beds such as flattening of the body, shortening of primary spines, multiplication of podia, and retention of the lantern of Aristotle into adulthood. To investigate the developmental basis of such morphological changes we documented the ontogeny of Clypeaster subdepressus. We obtained gametes from adult specimens by KCl injection and raised the embryos at 26C. Ciliated blastulae hatched 7.5 h after sperm entry. During gastrulation the archenteron elongated continuously while ectodermal red-pigmented cells migrated synchronously to the apical plate. Pluteus larvae began to feed in 3 d and were 20 d old at metamorphosis; starved larvae died 17 d after fertilization. Postlarval juveniles had neither mouth nor anus nor plates on the aboral side, except for the remnants of larval spicules, but their bilateral symmetry became evident after the resorption of larval tissues. Ossicles of the lantern were present and organized in 5 groups. Each group had 1 tooth, 2 demipyramids, and 2 epiphyses with a rotula in between. Early appendages consisted of 15 spines, 15 podia (2 types), and 5 sphaeridia. Podial types were distributed in accordance to Lovén's rule and the first podium of each ambulacrum was not encircled by the skeleton. Seven days after metamorphosis juveniles began to feed by rasping sand grains with the lantern. Juveniles survived in laboratory cultures for 9 months and died with wide, a single open sphaeridium per ambulacrum, aboral anus, and no differentiated food grooves or petaloids. Tracking the morphogenesis of early juveniles is a necessary step to elucidate the developmental mechanisms of echinoid growth and important groundwork to clarify homologies between irregular urchins