1,058 research outputs found

    Explicit large nuclear charge limit of electronic ground states for Li, Be, B, C, N, O, F, Ne and basic aspects of the periodic table

    Get PDF
    This paper is concerned with the Schrödinger equation for atoms and ions with N=1N=1 to 10 electrons. In the asymptotic limit of large nuclear charge ZZ, we determine explicitly the low-lying energy levels and eigenstates. The asymptotic energies and wavefunctions are in good quantitative agreement with experimental data for positive ions, and in excellent qualitative agreement even for neutral atoms (Z=NZ=N). In particular, the predicted ground state spin and angular momentum quantum numbers (1S^1S for He, Be, Ne, 2S^2S for H and Li, 4S^4S for N, 2P^2P for B and F, and 3P^3P for C and O) agree with experiment in every case. The asymptotic Schrödinger ground states agree, up to small corrections, with the semiempirical hydrogen orbital configurations developed by Bohr, Hund, and Slater to explain the periodic table. In rare cases where our results deviate from this picture, such as the ordering of the lowest 1Do^1D^o and 3So^3S^o states of the carbon isoelectronic sequence, experiment confirms our predictions and not Hund's

    Non-adiabatic transitions in multiple dimensions

    Get PDF

    A derivation of the Liouville equation for hard particle dynamics with non-conservative interactions

    Get PDF
    The Liouville equation is of fundamental importance in the derivation of continuum models for physical systems which are approximated by interacting particles. However, when particles undergo instantaneous interactions such as collisions, the derivation of the Liouville equation must be adapted to exclude non-physical particle positions, and include the effect of instantaneous interactions. We present the weak formulation of the Liouville equation for interacting particles with general particle dynamics and interactions, and discuss the results using an example

    Modelling inelastic granular media using Dynamical Density Functional Theory

    Get PDF
    We construct a new mesoscopic model for granular media using Dynamical Density Functional Theory (DDFT). The model includes both a collision operator to incorporate inelasticity and the Helmholtz free energy functional to account for external potentials, interparticle interactions and volume exclusion. We use statistical data from event-driven microscopic simulations to determine the parameters not given analytically by the closure relations used to derive the DDFT. We numerically demonstrate the crucial effects of each term in the DDFT, and the importance of including an accurately parametrised pair correlation function

    Canadian Chicken Industry: Consumer Preferences, Industry Structure and Producer Benefits from Investment in Research and Advertising

    Get PDF
    The Canadian chicken industry has operated under supply management since the mid-1970s. Canadian consumer preferences for chicken have grown dramatically since then possibly in response to concerns about health and the levels of fat and cholesterol in red meats. However Canadian consumers are also looking for convenience with their food purchases. Canadians are buying their chicken in frozen further processed forms, fresh by cut without skin and bone and in a variety of other different ways reflecting their unique willingness to pay for various attributes. There is also an increasing trend for retailers and processors to brand the fresh chicken product sold through grocery stores (for example, Maple Leaf Prime). The preferences Canadian consumer have for various chicken products, the prices they are comfortable paying and the strategies followed by processors/retailers can directly affect the outcomes of industry wide strategies such as investment in generic advertising and research or the impact of international market changes such as border closures. This research is an initial attempt to quantify Canadian consumer preferences – for fresh product by type – for product by level of processing – for chicken product by cut - for fresh chicken by brand - to examine the impact of substitutability on a variety of market shocks. The various different disaggregations of Canadian chicken consumption are used in a number of simulation models to illustrate how important preferences are to producer returns when there are market shocks. If Canadians found all chicken products available in the grocery store to be perfectly substitutable then previous policy analysis assuming chicken is one homogeneous product would be sufficient for industry policy analysis purposes. If Canadians view all the different chicken products as imperfectly substitutable and given that various chicken products are produced in relatively fixed proportions (white and dark meat, for example) further understanding of how consumers make their purchase decisions could enhance the industries ability to predict outcomes. For example, border closing to Canadian exports ( as a result of an Avian influenza outbreak, for example) would result in a significant increase in the dark meat products available for sale through Canadian grocery stores. The results presented in this research could provide a clue as to how much dark meat prices might decline while white meat prices might remain unaffected. The results reported suggest that at the consumer level, chicken fresh and frozen products are not perceived to be perfect substitutes, within a narrow category such as fresh chicken breasts, they are not perceived as even close substitutes, within the fresh category branded products such as those developed by Lilydale and Maple Leaf are not perceived as perfect substitutes. As well, an initial look at the demand for individual chicken products by household suggests that there is far from a common buying pattern across Canadian households, even within a single province. The results also suggest that health and convenience attributes are driving Canadian consumer preferences. Simulation results highlight the fact that pricing strategies followed by major processors/retailers within Canada can influence the returns to generic advertising and research. Further research could provide additional robust estimates of the chicken product substitutability existing in the Canadian market and an increased understanding of the market characteristics currently operating. The results presented here suggest that further work in this area is important for the chicken industry to pursue.consumer behaviour, chicken consumption, differentiated products, Consumer/Household Economics, Demand and Price Analysis, Food Consumption/Nutrition/Food Safety, Marketing, D12, Q11, Q18,

    An exploration of decision-making by individuals who have received specialized treatment for early psychosis

    Get PDF
    Decision-making is a critical life skill, integral for guiding behaviour. Previous research has demonstrated that decision-making is frequently impaired across a range of psychiatric disorders including schizophrenia. Although a concerted research effort has recently been focused on understanding decision-making in chronic schizophrenia, the current study was conceived to provide an initial exploration into the decision-making process of individuals who received specialized treatment for early psychosis. We investigated the decision-making ability of 16 patients enrolled in an early psychosis (EP) program and 20 healthy controls based upon their performance on the Iowa Gambling Task (IGT) and Game of Dice Task (GDT). Additional measures of neuropsychological functioning were also examined. Differences in ambiguous decision-making (IGT) were observed, with the EP group performing significantly worse than the healthy control group. Additionally, there were no differences between the two groups observed in risky decision-making (GDT). The only neuropsychological variable that correlated with decision-making performance across tasks was that of working memory. More specifically, measures of IGT ability significantly correlated with working memory performance for the EP group but not the healthy controls. As such, the current study illustrates an important role for working memory in making ambiguous decisions. It is possible that individuals with EP experience difficulty maintaining mental representations of expected value. Therefore, it is more difficult to utilize feedback from the previous trials to impact positively on future choices and rewards that are not immediately present in the environment. The clinical implications of these findings are discussed for understanding decision-making by individuals who experienced early psychosis, and how decision-making impairments could be accommodated for by treatment programs
    corecore