Analysis of the carbon and nitrogen limitations to soybean yield

Soybeans are hypothesized to be “self-destructive” since they apparently need to translocate large amounts of nitrogen from vegetative tissues during seed-fill to sustain seed growth. To assess the possible limitations of this characteristic on soybean seed yield, a simple, dynamic simulation model is developed which accounts for the availability of nitrogen and photosynthate within the plant. The simulations show that the duration of seedfill and seed yield is clearly limited by the self-destructive characteristic. Increased availability of nitrogen within the plant is required for significant increases in soybean yields. Possible alterations of the model required to mimic actual soybean seed growth are presented

A re-appraisal of the fertility response to the Australian baby bonus

The Australian baby bonus offering parents $3,000 on the birth of a new child was announced on May 11 2004. The availability of five years of birth data following the introduction of the baby bonus allows for a more comprehensive analysis of the policy implications than is current in the literature. The focus of this paper is to identify if there is a positive fertility choice response to the introduction of the Australian baby bonus policy and if this response is sustained over time. To do this 19 years of birth and macroeconomic data, beginning 1990, is analysed using an unobservable components model. The results indicate a significant increase in birth numbers ten months following the announcement of the baby bonus, and this overall increase was sustained up to the end of the observed period. A cumulative growth in birth numbers which commenced in January 2006 slows in 2008 and 2009. It is suggested that the initial increase in births, identified in March 2005, is a direct fertility response to the introduction of the policy and that the subsequent change in the growth of birth numbers may be the result of a delayed effect working through a number of channels. It is estimated that approximately 119,000 births are attributable to the baby bonus over the period, at an approximate cost of$39000 per extra child.Fertility Rate, Time Series, baby bonus

Informational Regulation of Industrial Safety - An Examination of the U.S. "Local Emergency Planning Committees"

A major trend in the regulation of industrial risks to human health and the environment is the provision of relevant information to (and the empowerment of) all stakeholders and risk bearers. This paper provides a concrete look at one of the key items in implementing this "regulation by information" in the United States: the so-called LEPCs or Local Emergency Planning Committees. We summarize the literature on the subject, report on some interviews we made at selected LEPCs in the states of Vermont and Maryland, and present preliminary figures from a recent survey we just completed of more than 200 LEPCs. The ending sections also contain some international comparisons and an appraisal of the actual LEPCs. La nouvelle tendance dans les réglementations concernant les risques industriels à la santé humaine et à l'environnement est de diffuser l'information pertinente à toutes les parties prenantes. Cet article considère l'un des outils clés de cette « régulation des risques par l'information » : les comités locaux de planification d'urgence, aux Etats-Unis (désignés en anglais par le sigle LEPC). Nous dressons un bilan de la littérature sur le sujet. Nous intégrons des éléments importants résultant d'entrevues faites auprès de LEPCs sélectionnés dans les États du Vermont et du Maryland. Et nous présentons certains résultats préliminaires d'une enquête récente que nous venons de réaliser auprès de plus de 200 LEPCs. Les sections finales contiennent également plusieurs comparaisons internationales et une appréciation du fonctionnement actuel des LEPCs.Chemical plant safety, Community participation, US Emergency Planning and Community Right-To-Know Act, Clean Air Act, Local Emergency Planning Committees (LEPCs), Risk Management Program, Stakeholders involvement, Sûreté des usines chimiques, participation du public, US Emergency Planning and Community Right-To-Know Act (EPCRA), Clean Air Act, Comités locaux de planification d'urgence (LEPC), Programme de gestion de risque, Implication des parties prenantes

A method to study complex systems of mesons in Lattice QCD

Finite density systems can be explored with Lattice QCD through the calculation of multi-hadron correlation functions. Recently, systems with up to 12 $\pi^+$'s or $K^+$'s have been studied to determine the 3-$\pi^+$ and 3-$K^+$ interactions, and the corresponding chemical potentials have been determined as a function of density. We derive recursion relations between correlation functions that allow this work to be extended to systems of arbitrary numbers of mesons and to systems containing many different types of mesons, such as $\pi^+$'s, $K^+$'s, $\bar{D}^0$'s and $B^+$'s. These relations allow for the study of finite-density systems in arbitrary volumes, and for the study of high-density systems.Comment: JLAB-THY-10-1121, NT@UW-10-01, journal versio

Lattice QCD at non-zero isospin chemical potential

Quantum chromodynamics (QCD) at non-zero isospin chemical potential is studied in a canonical approach by analyzing systems of fixed isospin number density. To construct these systems, we develop a range of new algorithms for performing the factorially large numbers of Wick contractions required in multi-hadron systems. We then use these methods to study systems with the quantum numbers of up to 72 $\pi^+$'s on three ensembles of gauge configurations with spatial extents $L\sim$ 2.0, 2.5 and 3.0 fm, and light quark masses corresponding to a pion mass of {390 MeV}. The ground state energies of these systems are extracted and the volume dependence of these energies is utilized to determine the two- and three- body interactions amongst $\pi^+$'s. The systems studied correspond to isospin densities of up to $\rho_I\sim 9\ {\rm fm}^{-3}$ and probe isospin chemical potentials, $\mu_I$, in the range m_\pi\ \lsim \mu_I\ \lsim 4.5\ m_\pi, allowing us to investigate aspects of the QCD phase diagram at low temperature and for varying isospin chemical potential. By studying the energy density of the system, we provide numerical evidence for the conjectured transition of the system to a Bose-Einstein condensed phase at \mu_I\ \gsim m_\pi.Comment: 32 pages, 22 figure

The finite temperature transition for 3-flavour lattice QCD at finite isospin density

We simulate 3-flavour lattice QCD with a small chemical potential $\mu_I$ for isospin, at temperatures close to the finite temperature transition. Using quark masses just above the critical mass for zero chemical potential, we determine the position of the transition from hadronic matter to a quark-gluon plasma as a function of $\mu_I$. We see evidence for a critical endpoint where the transition changes from a crossover to a first-order transition as $\mu_I$ is increased. We argue that QCD at finite $\mu_I$ and QCD at finite quark-numberchemical potential $\mu$ should behave similarly in this region.Comment: 3 pages LaTex, 2 postscript figures. Parallel talk presented at Lattice 2004 (non-zero), Fermila

Effect of gain and phase errors on SKA1-low imaging quality from 50-600 MHz

Simulations of SKA1-low were performed to estimate the noise level in images produced by the telescope over a frequency range 50-600 MHz, which extends the 50-350 MHz range of the current baseline design. The root-mean-square (RMS) deviation between images produced by an ideal, error-free SKA1-low and those produced by SKA1-low with varying levels of uncorrelated gain and phase errors was simulated. The residual in-field and sidelobe noise levels were assessed. It was found that the RMS deviations decreased as the frequency increased. The residual sidelobe noise decreased by a factor of ~5 from 50 to 100 MHz, and continued to decrease at higher frequencies, attributable to wider strong sidelobes and brighter sources at lower frequencies. The thermal noise limit is found to range between ~10 - 0.3 $\mu$Jy and is reached after ~100-100 000 hrs integration, depending on observation frequency, with the shortest integration time required at ~100 MHz.Comment: 23 pages, 11 figures Typo correcte

Lattice QCD at finite isospin density and/or temperature

We simulate two-flavour lattice QCD with at a finite chemical potential $\mu_I$ for isospin, and finite temperature. At small $\mu_I$, we determine the position of the crossover from hadronic matter to a quark-gluon plasma as a function of $\mu_I$. At larger $\mu_I$ we observe the phase transition from the superfluid pion-condensed phase to a quark-gluon plasma, noting its change from second order to first order as $\mu_I$ is increased. We also simulate two-flavour lattice QCD at zero quark mass, using an action which includes an additional 4-fermion interaction, at temperatures close to the chiral transition on $N_t=8$ lattices.Comment: 3 pages LaTex, 3 postscript figures. Parallel talk at Lattice2003(nonzero