27,075 research outputs found
Economic Growth and Threatened and Endangered Species Listings: A VAR Analysis
We conduct several analyses to examine the link between threatened and endangered species listings and macroeconomic activity. Preliminary tests using ordinary least squares are run on both time series data on the national level and cross sectional data at the state level. The analysis is then extended using vector autoregressive (VAR) techniques. VAR results, impulse response functions and variance decompositions are reported to shed more light on the causal relationships between threatened and endangered species, GDP and population. Our results indicate that there is little or no empirical evidence that GDP growth rates lead to changes in the number of threatened and endangered species listings.
Economic Growth and Threatened and Endangered Species Listings: A VAR Analysis
We conduct several analyses to examine the link between threatened and endangered species listings and macroeconomic activity. Preliminary tests using ordinary least squares are run on both time series data on the national level and cross sectional data at the state level. The analysis is then extended using vector autoregressive (VAR) techniques. VAR results, impulse response functions and variance decompositions are reported to shed more light on the causal relationships between threatened and endangered species, GDP and population. Our results indicate that there is little or no empirical evidence that GDP growth rates lead to changes in the number of threatened and endangered species listings. Key Words: Economic growth, endangered and threatened species, vector autoregression
Sprue cutoff tool for molded FCC plugs
Sprue removal operation is accomplished by positioning plug on tool bed, adjusting blades, and moving handle down for cutting process. Blades are raised to remove trimmed plug
Seating tool for preparing molded-plug terminations on FCC
Hand-operated tool positions and seats window piece and conductor spacer onto conductors of two stripped cables during process of terminating cables with molded plug. Tool accommodates cables up to 3 in. wide and is used in conjunction with folding tools
Stochastic Dominance, Entropy and Biodiversity Management
In this paper we develop a model of population dynamics using the Shannon entropy index, a measure of diversity that allows for global and specific population shocks. We model the effects of increasing the number of parcels on biodiversity, varying the number of spatially diverse parcels to capture risk diversification. We discuss the concepts of stochastic dominance as a means of project selection, in order to model biodiversity returns and risks. Using a Monte Carlo simulation we find that stochastic dominance may be a useful theoretical construct for project selections but it is unable to rank every case.
A Simplified Mathematical Model for the Formation of Null Singularities Inside Black Holes I - Basic Formulation and a Conjecture
Einstein's equations are known to lead to the formation of black holes and
spacetime singularities. This appears to be a manifestation of the mathematical
phenomenon of finite-time blowup: a formation of singularities from regular
initial data. We present a simple hyperbolic system of two semi-linear
equations inspired by the Einstein equations. We explore a class of solutions
to this system which are analogous to static black-hole models. These solutions
exhibit a black-hole structure with a finite-time blowup on a characteristic
line mimicking the null inner horizon of spinning or charged black holes. We
conjecture that this behavior - namely black-hole formation with blow-up on a
characteristic line - is a generic feature of our semi-linear system. Our
simple system may provide insight into the formation of null singularities
inside spinning or charged black holes in the full system of Einstein
equations.Comment: 39 pages, 3 figures, extended versio
Formation of terrestrial planets in close binary systems: the case of Alpha Centauri A
At present the possible existence of planets around the stars of a close
binary system is still matter of debate. Can planetary bodies form in spite of
the strong gravitational perturbations of the companion star? We study in this
paper via numerical simulation the last stage of planetary formation, from
embryos to terrestrial planets in the Alpha Cen system, the prototype of close
binary systems. We find that Earth class planets can grow around Alpha Cen A on
a time-scale of 50 Myr. In some of our numerical models the planets form
directly in the habitable zone of the star in low eccentric orbits. In one
simulation two of the final planets are in a 2:1 mean motion resonance that,
however, becomes unstable after 200 Myr. During the formation process some
planetary embryos fall into the stars possibly altering their metallicity.Comment: accepted for pubblication in A&A, 13 pages, 9 figure
Stochastic Dominance, Entropy and Biodiversity Management
In this paper we develop a model of population dynamics using the Shannon entropy index, a measure of diversity that allows for global and specific population shocks. We model the effects of increasing the number of parcels on biodiversity, varying the number of spatially diverse parcels to capture risk diversification. We discuss the concepts of stochastic dominance as a means of project selection, in order to model biodiversity returns and risks. Using a Monte Carlo simulation we find that stochastic dominance may be a useful theoretical construct for project selections but it is unable to rank every case. Key Words: Stochastic Dominance, Entropy, Biodiversity Management
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