Aggregating Elasticities: Intensive and Extensive Margins of Female Labour Supply

There is a renewed interest in the size of labour supply elasticities and the discrepancy between micro and macro estimates. Recent contributions have stressed the distinction between changes in labour supply at the extensive and the intensive margin. In this paper, we stress the importance of individual heterogeneity and aggregation problems. At the intensive margins, simple specifications that seem to fit the data give rise to non linear expressions that do not aggregate in a simple fashion. At the extensive margin, aggregate changes in participation are likely to depend on the cross sectional distribution of state variables when a shock hits and, therefore, are likely to be history dependent. We tackle these aggregation issues directly by specifying a life cycle model to explain female labour supply in the US and estimate its various components. We estimate the parameters of different component of the model. Our results indicate that (i) at the intensive margin, Marshallian and Hicksian elasticities are very heterogeneous and, on average, relatively large; (ii) Frisch elasticities are, as implied by the theory, even larger; (iii) aggregate labour supply elasticities seem to vary over the business cycle, being larger during recessions

Failure of Intravenous Morphine to Serve as an Effective Instrumental Reinforcer in Dopamine D2 Receptor Knock-Out Mice

The rewarding effects of opiates are thought to be mediated through dopaminergic mechanisms in the ventral tegmental area, dopamine-independent mechanisms in the nucleus accumbens, or both. The purpose of the present study was to explore the contribution of dopamine to opiate-reinforced behavior using D2 receptor knock-out mice. Wild-type, heterozygous, and D2 knock-out mice were first trained to lever press for water reinforcement and then implanted with intravenous catheters. The ability of intravenously delivered morphine to maintain lever pressing in these mice was studied under two schedules of reinforcement: a fixed ratio 4 (FR4) schedule (saline, 0.1, 0.3, or 1.0 mg/kg, per injection) and a progressive ratio (PR) schedule (1.0 mg/kg, per injection). In the wild-type and heterozygous mice, FR4 behavior maintained by morphine injections was significantly greater than behavior maintained by vehicle injections. Response rate was inversely related to injection dose and increased significantly in the wild-type and heterozygous mice when the animals were placed on the PR schedule. In contrast, the knock-out mice did not respond more for morphine than for saline and did not respond more when increased ratios were required by the PR schedule. Thus, morphine served as a positive reinforcer in the wild-type and heterozygous mice but failed to do so in the knock-out mice. Under this range of doses and response requirements, the rewarding effects of morphine appear to depend critically on an intact D2 receptor systemFil: Elmer, Greg I.. University of Maryland; Estados UnidosFil: Pieper, Jeanne O.. National Institutes of Health; Estados UnidosFil: Rubinstein, Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Low, Malcolm J.. Oregon Health and Sciences University; Estados UnidosFil: Grandy, David K.. Oregon Health and Sciences University; Estados UnidosFil: Wise, Roy A.. National Institutes of Health; Estados Unido

Concepts in Order Statistics and Bayesian Estimation

In this paper, some basic concepts related to order statistics and Bayesian estimation is discussed which includes tests of life, order statistics and concept of reconstruction that has various fields in the application such as reconstruction for industrial units or organisms. This paper also describes significant functions in the reconstruction such as probability of life function or failure probability function, surviving probability function, life probability density function and failure rate function. Furthermore, it illustrated in depth idea concerning Bayesian statistics for the study and evaluation of different Bayesian methods. Keywords Bayesian statistics, failure probability function, order statistic

Low temperature relations in QCD

In this talk I discuss the low temperature relations for the trace of the energy-momentum tensor in QCD with two and three quarks. It is shown that the temperature derivatives of the anomalous and normal (quark massive term) contributions to the trace of the energy-momentum tensor in QCD are equal to each other in the low temperature region. Leading corrections connected with $\pi\pi$-interactions and thermal excitations of $K$ and $\eta$ mesons are calculated.Comment: 10 pages, LaTeX2e. Talk given at 12th International Seminar on High-Energy Physics (QUARKS 2002), Novgorod, Russia, 1-7 Jun 200

Fish farm effluent as a nutrient source for algae biomass cultivation

One of the challenges of microalgae biotechnology is the cost of growth media nutrients, with microalgae consuming enormous quantities of fertilisers, more than other oil crops. The traditional use of synthetic fertilisers in mass cultivation of microalgae is associated with rising prices of crude oil and competition from traditional agriculture. The fact that fish farm wastewater (FFW) nutrients are released in the form preferred by microalgae (NH3 for nitrogen and PO4 -3 for phosphate), and the ability of microalgae to use nitrogen from different sources, can be exploited by using fish farm effluent rich in nutrients (nitrogen and phosphorus) in the cultivation of cheaper microalgae biomass for production of biodiesel. The cultivationof algae biomass in FFW will also serve as wastewater treatment. We reviewed the benefits and potential of fish effluent in algae cultivation for the production of biodiesel. Microalgae can utilise nutrients in FFW for different applications desirable for the production of biomass, including the accumulation of lipids, and produce a fuel with desirable properties. Also, treating wastewater and reducing demand for fresh water are advantageous. The high lipid content and comparable biodiesel properties of Chlorella sorokiniana and Scenedesmus obliquus make both species viable for FFW cultivation for biodiesel production. Significance: The cost associated with microalgae growth media nutrients can be saved by using fish farm wastewater,which contains nutrients (nitrogen and phosphorus) suitable for microalgae cultivation. Fish farm wastewater has lower nutrient concentrations when compared to standard growth media suitable for higher lipid accumulation. Microalgae used as a biodiesel feedstock, cultivated in fish farm wastewater, has added benefits, including wastewater treatment

Modeling H2 formation in the turbulent ISM: Solenoidal versus compressive turbulent forcing

We present results from high-resolution three-dimensional simulations of the turbulent interstellar medium that study the influence of the nature of the turbulence on the formation of molecular hydrogen. We have examined both solenoidal (divergence-free) and compressive (curl-free) turbulent driving, and show that compressive driving leads to faster H2 formation, owing to the higher peak densities produced in the gas. The difference in the H2 formation rate can be as much as an order of magnitude at early times, but declines at later times as the highest density regions become fully molecular and stop contributing to the total H2 formation rate. We have also used our results to test a simple prescription suggested by Gnedin et al. (2009) for modeling the influence of unresolved density fluctuations on the H2 formation rate in large-scale simulations of the ISM. We find that this approach works well when the H2 fraction is small, but breaks down once the highest density gas becomes fully molecular.Comment: 13 pages, 8 figures, accepted for publication in MNRA

On the Relationship Between Molecular Hydrogen and Carbon Monoxide Abundances in Molecular Clouds

The most usual tracer of molecular gas is line emission from CO. However, the reliability of that tracer has long been questioned in environments different from the Milky Way. We study the relationship between H2 and CO abundances using a fully dynamical model of magnetized turbulence coupled to a chemical network simplified to follow only the dominant pathways for H2 and CO formation and destruction, and including photodissociation using a six-ray approximation. We find that the abundance of H2 is primarily determined by the amount of time available for its formation, which is proportional to the product of the density and the metallicity, but insensitive to photodissociation. Photodissociation only becomes important at extinctions under a few tenths of a visual magnitude, in agreement with both observational and prior theoretical work. On the other hand, CO forms quickly, within a dynamical time, but its abundance depends primarily on photodissociation, with only a weak secondary dependence on H2 abundance. As a result, there is a sharp cutoff in CO abundance at mean visual extinctions A_V < 3. At lower values of A_V we find that the ratio of H2 column density to CO emissivity X_CO is proportional to A_V^(-3.5). This explains the discrepancy observed in low metallicity systems between cloud masses derived from CO observations and other techniques such as infrared emission. Our work predicts that CO-bright clouds in low metallicity systems should be systematically larger or denser than Milky Way clouds, or both. Our results further explain the narrow range of observed molecular cloud column densities as a threshold effect, without requiring the assumption of virial equilibrium.Comment: 16 pages, 11 figures. Updated to match version accepted by MNRA

Fluctuations in coral health of four common inshore reef corals in response to seasonal and anthropogenic changes in water quality

Environmental drivers of coral condition (maximum quantum yield, symbiont density, chlorophyll a content and coral skeletal growth rates) were assessed in the equatorial inshore coastal waters of Singapore, where the amplitude of seasonal variation is low, but anthropogenic influence is relatively high. Water quality variables (sediments, nutrients, trace metals, temperature, light) explained between 52 and 83% of the variation in coral condition, with sediments and light availability as key drivers of foliose corals (Merulina ampliata, Pachyseris speciosa), and temperature exerting a greater influence on a branching coral (Pocillopora damicornis). Seasonal reductions in water quality led to high chlorophyll a concentrations and maximum quantum yields in corals, but low growth rates. These marginal coral communities are potentially vulnerable to climate change, hence, we propose water quality thresholds for coral growth with the aim of mitigating both local and global environmental impacts