Latin America in the rearview mirror

Latin American countries are the only Western countries that are poor and that aren't gaining ground on the United States. This paper evaluates why Latin America has not replicated Western economic success. We find that this failure is primarily due to TFP differences. Latin America's TFP gap is not plausibly accounted for by human capital differences, but rather reflects inefficient production. We argue that competitive barriers are a promising channel for understanding low Latin TFP. We document that Latin America has many more international and domestic competitive barriers than do Western and successful East Asian countries. We also document a number of microeconomic cases in Latin America in which large reductions in competitive barriers increase productivity to Western levels.Latin America - Economic conditions

Relative Forage Yield of Intercropped Lucerne (\u3ci\u3eMedicago sativa\u3c/i\u3e L.) And Winter Forage Cereals

In tropical regions of the world intercropping is mainly associated with the production of maize for grain, while in temperate areas it is associated with the efficient production of forage. There is increasing interest in the development of cereal - legume intercropping in some temperate regions (reviewed by Mason & Pritchard, 1987). The aim of this study was to compare the relative forage yield of intercropped lucerne and cereal

Latin America in the Rearview Mirror

Latin American countries are the only Western countries that are poor and that aren't gaining ground on the United States. This paper evaluates why Latin America has not replicated Western economic success. We find that this failure is primarily due to TFP differences. Latin America's TFP gap is not plausibly accounted for by human capital differences, but rather reflects inefficient production. We argue that competitive barriers are a promising channel for understanding low Latin TFP. We document that Latin America has many more international and domestic competitive barriers than do Western and successful East Asian countries. We also document a number of microeconomic cases in Latin America in which large reductions in competitive barriers increase productivity to Western levels.

Can Maxwell's equations be obtained from the continuity equation?

We formulate an existence theorem that states that given localized scalar and vector time-dependent sources satisfying the continuity equation, there exist two retarded fields that satisfy a set of four field equations. If the theorem is applied to the usual electromagnetic charge and current densities, the retarded fields are identified with the electric and magnetic fields and the associated field equations with Maxwell's equations. This application of the theorem suggests that charge conservation can be considered to be the fundamental assumption underlying Maxwell's equations.Comment: 14 pages. See the comment: "O. D. Jefimenko, Causal equations for electric and magnetic fields and Maxwell's equations: comment on a paper by Heras [Am. J. Phys. 76, 101 (2008)].

Tillage Systems in the Establishment of Pastures in Argentinian Subhumid Area

The effect of three tillage systems on the number of plants produced and forage production of a pasture the first year of establishment was assessed in this experiment. The components of the pasture were alfalfa (Medicago sativa L.), tall fescue (Festuca arundinacea Shreb), orchard grass (Dactilys glomerata L), and prairie grass (Bromus unioloides). Treatments were three tillage systems: conventional tillage (CT), reduced tillage (RT), and direct sowing (DS). Sowing was performed with (NI) and without fertilizers (N0) in each treatment. A split-plot experimental design with two repetitions was used, with tillage being the main factor and the fertilization levels the secondary one. Results were subjected to ANOVA while means were compared by the Duncan Test Counts. These were conducted 90 days after sowing to determine the number of emerged alfalfa and grass seedlings. In November, before starting direct grazing, hand cut samples were taken to determine total biomass and also biomass production of each component of the pasture. Total stand plant and grass stand, was significantly affected (P \u3c 0.05) by the tillage factor. Forage production of both alfalfa and grass, and total production was higher with conventional tillage (CT) and differed significantly (P \u3c 0.05) from direct sowing (DS). The fertilizing effect and its interaction with the tillage factor was not statistically significant (P \u3c 0.05) for any of the components measured. Results indicate that direct sowing seems to condition grass plant stand and forage production of each of the pasture components in the year of establishment

Prediction and measurement of radiation damage to CMOS devices on board spacecraft

The CMOS Radiation Effects Measurement (CREM) experiment is presently being flown on the Explorer-55. The purpose of the experiment is to evaluate device performance in the actual space radiation environment and to correlate the respective measurements to on-the-ground laboratory irradiation results. The experiment contains an assembly of C-MOS and P-MOS devices shielded in front by flat slabs of aluminum and by a practically infinite shield in the back. Predictions of radiation damage to C-MOS devices are based on standard environment models and computational techniques. A comparison of the shifts in CMOS threshold potentials, that is, those measured in space to those obtained from the on-the-ground simulation experiment with Co-60, indicates that the measured space damage is smaller than predicted by about a factor of 2-3 for thin shields, but agrees well with predictions for thicker shields

Cosmological Relativity: A General-Relativistic Theory for the Accelerating Expanding Universe

Recent observations of distant supernovae imply, in defiance of expectations, that the universe growth is accelerating, contrary to what has always been assumed that the expansion is slowing down due to gravity. In this paper a general-relativistic cosmological theory that gives a direct relationship between distances and redshifts in an expanding universe is presented. The theory is actually a generalization of Hubble's law taking gravity into account by means of Einstein's theory of general relativity. The theory predicts that the universe can have three phases of expansion, decelerating, constant and accelerating, but it is shown that at present the first two cases are excluded, although in the past it had experienced them. Our theory shows that the universe now is definitely in the stage of accelerating expansion, confirming the recent experimental results

Biomass Vertical Distribution in a Grazed Grassland Under Monoespecific and Mixed Grazing

Mixed grazing is defined as the use of the same forage resource for more than one herbivore species. It has been shown that different herbivore species have specific grazing modalities (Black and Kenney, 1984), which may differentially modify the structure of the pasture. The aim of this study was to evaluate the biomass vertical distribution in a sward with mixed grazing

Extreme gravitational lensing in vicinity of Schwarzschild-de Sitter black holes

We have developed a realistic, fully general relativistic computer code to simulate optical projection in a strong, spherically symmetric gravitational field. The standard theoretical analysis of optical projection for an observer in the vicinity of a Schwarzschild black hole is extended to black hole spacetimes with a repulsive cosmological constant, i.e, Schwarzschild-de Sitter spacetimes. Influence of the cosmological constant is investigated for static observers and observers radially free-falling from the static radius. Simulations include effects of the gravitational lensing, multiple images, Doppler and gravitational frequency shift, as well as the intensity amplification. The code generates images of the sky for the static observer and a movie simulations of the changing sky for the radially free-falling observer. Techniques of parallel programming are applied to get a high performance and a fast run of the BHC simulation code

Bohmian Quantum Gravity in the Linear Field Approximation

In this paper we have applied Bohmian quantum theory to the linear field approximation of gravity and present a self--consistent quantum gravity theory in the linear field approximation. The theory is then applied to some specific problems, the Newtonian limit, and the static spherically symmetric solution. Some observable effects of the theory are investigated