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In this study, hierarchically structured mesoporous Fe3O4 nanospheres were synthesized using a solvothermal method and the application of the obtained Fe3O4 nanospheres in magnetorheological (MR) fluid was investigated in detail. The morphology, microstructure and magnetic properties of the as-synthesized Fe3O4 nanospheres were examined through different characterization techniques, such as SEM, TEM, XRD, XPS, BET and SQUID. The results of rheological measurements revealed that the prepared homogeneous MR fluid based on mesoporous Fe3O4 nanospheres showed typical MR performances, exhibiting a rapid and reversible transition from a liquid-like to a solid-like state under the action of an external magnetic field. More importantly, it should be noted that the Fe3O4 nanospheres-based MR fluid demonstrated enhanced a sedimentation stability as compared to that of carbonyl iron (CI) particles-based MR fluid. This finding was probably assigned to the particular mesoporous structure and the decreased density mismatch between two components of MR fluid.

The environmental consequences of residue removal practices to support cellulosic biofuel production remain poorly understood. In the U.S. Midwest, corn (Zea mays L.) stover removal combined with no-till practices may increase or decrease soil N2O emissions by influencing soil moisture, temperature, and nutrient dynamics, yet empirical evidence from long-term field experiments is inconsistent. We investigated the effects of residue management (residue retained or removed) and tillage (chisel-till or no-till) on cumulative soil nitrous oxide (N2O) emissions, grain yield, and yield-scaled N2O emissions in a 3-year study initiated 10years after treatment implementation in a long-term, continuous corn experiment in Illinois, United States. Crop yields were affected by treatment in only one of three study years, with the combination of residue removal and no-till reducing yields compared to both chisel-till treatments. Cumulative N2O emissions, soil inorganic N concentrations, and yield-scaled N2O emissions differed over the 3-year period and were significantly affected by tillage, with no response to residue management. In 2years, no-till decreased cumulative N2O emissions and yield-scaled N2O emissions by an average of 64% and 60%, respectively. Correlations between daily N2O fluxes and soil moisture, temperature, and inorganic N concentrations suggested that the relative importance of these variables changed depending on year and treatment. While more research across a range of sites and management practices is needed, our findings support previous studies which have challenged IPCC methodology assumptions regarding the effects of residue removal on N2O emissions. We conclude there is inherent difficulty in predicting the impacts of residue removal due to the complexity of soil processes underlying N2O emissions coupled with inter-annual weather variability in this rainfed continuous corn system. Future efforts to evaluate the net greenhouse gas emissions of cellulosic biofuel production may benefit from accounting for this uncertainty.

The authors apply the asset-valuation model developed by Rabinovitch (1989) to six publicly traded Canadian banks over the period 1982–2002. The model is an extension of the Merton (1977a) option-pricing model with the incorporation of stochastic interest rates. The authors introduce the Z-score, a measure of distance-to-default, which can be a useful tool for regulators in assessing the risk of bank failures. The Z-scores, overall, suggest that Canadian banks are far from the point of default. The authors also find that both the market valuation of the bank assets and the Z-score of the Canadian banks demonstrate similar regime shifts in the late 1990s, which may be related to regulatory changes during the 1990s., Pour la période allant de 1982 à 2002, les auteurs appliquent à six banques canadiennes inscrites en bourse le modèle d'évaluation des actifs proposé par Rabinovitch (1989). Ce modèle reprend la formule d'évaluation des options de Merton (1977a) en y intégrant des taux d'intérêt stochastiques. Les auteurs présentent une mesure de la distance qui sépare une banque donnée d'un défaut de paiement — le score Z — dont les autorités réglementaires pourraient se servir pour apprécier le risque de défaillance des établissements bancaires. Dans l'ensemble, les scores Z obtenus indiquent que les banques canadiennes sont éloignées du point de défaillance. Les auteurs observent en outre des changements de régime analogues dans les séries relatives à la valeur marchande des actifs et au score Z des banques durant la deuxième moitié des années 1990, lesquels pourraient être attribuables aux modifications apportées à la réglementation au courant de cette décennie.

In this paper, we analyze the dynamic behaviour of employment and hours worked per worker in a stochastic general equilibrium model with a matching mechanism between vacancies and unemployed workers. The model is estimated for the United States using the Generalized Methods of Moments (GMM) estimation technique. An increase in government spending raises hours worked per worker, and crowds out private consumption due to a negative wealth effect. On the path converging towards the steady state, private consumption is below its long-run average and increases, which implies that the interest rate is above its long-run average and declines. The interest rate effect dominates the pure economic rent effect on the capital value of a hired worker to the firm, causing a reduction of job openings and consequently a decrease in employment. These results are contrasted with the predictions of a version of the Burnside, Eichenbaum and Rebelo's (1993) labor hoarding model., Les auteurs de l'étude analysent le comportement dynamique de l'emploi et du nombre d'heures travaillées par travailleur dans le cadre d'un modèle stochastique d'équilibre général doté d'un mécanisme d'appariement des postes vacants et des chômeurs. Le modèle est estimé pour les États-Unis à l'aide de la méthode des moments généralisés. Une hausse des dépenses publiques entraîne une augmentation du nombre d'heures travaillées par travailleur et provoque l'éviction d'une partie de la consommation privée par le jeu d'un effet de richesse négatif. Durant le processus d'ajustement vers le régime permanent, la consommation privée se situe sous sa moyenne à long terme et augmente graduellement, ce qui implique que le taux d'intérêt est supérieur à sa moyenne à long terme et baisse progressivement. L'effet du taux d'intérêt l'emporte sur celui de la rente économique pure dans la détermination de la valeur en capital d'un travailleur pour l'entreprise, d'où une réduction du nombre de postes disponibles et une diminution consécutive de l'emploi. Les auteurs comparent ces résultats aux prévisions d'une version du modèle de thésaurisation de la main-d'oeuvre de Burnside, Eichenbaum et Rebelo (1993).

This thesis studies the effects of fiscal and labour market policies on the labour market activities. The study is based on a general equilibrium framework. The models considered in this thesis are built on the recent advances of growth models which incorporate labour market search/match activities. This study extends the previous models to address several important empirical issues.;In Chapter 1, an empirical study using multivariate vector autoregression (VAR) models shows that, in postwar U.S., employment and hours worked per worker respond differently to a temporary shock in government consumption. The shock raises hours worked per worker and reduces employment. The existing standard neoclassical growth models have mainly focused on total hours effects of a government spending shock, rather than separate employment and hours effects. In this chapter, we analyze the dynamic behaviour of employment and hours worked per worker in a stochastic general equilibrium model with a matching mechanism between vacancies and unemployed workers. The model is estimated for U.S. using the Generalized Methods of Moments (GMM) estimation technique and the responses of employment and hours worked per worker are qualitatively similar to those in the VAR models. An increase in government spending raises hours worked per worker, and crowds out private consumption due to a negative wealth effect. On the path converging towards the steady state, private consumption is below its long run average and increasing, which implies that the interest rate is above its long run average and declining. The higher interest rates lower the capital value of a hired worker to the firm, causing a reduction of job openings and consequently a decrease in employment.;Chapter 2 involves a study of quantifying the potential causes of the rising unemployment rate in Canada over the past three decades based on a general equilibrium catch model. Several policy variables which are considered to be influential to unemployment are incorporated in the model. They are labour income taxes, capital income taxes, payroll taxes, unemployment benefits, and advance notice and several payment regulations. In order to evaluate the relative importance of changes in government policies, we also consider the impact of changes in productivity growth. We find that fiscal and labour market policies have only a limited effect in the model economy.;Chapter 3 compares the cost-effectiveness of the Investment Tax Credit (ITC) program and the Payroll Tax Credit (PTC) program. The ITC increases employment by increasing marginal labour productivity, while the PTC increases employment by directly reducing labour cost. This chapter compares the consequences of an introduction of the Investment Tax Credit (ITC) program or the Payroll Tax Credit (PTC) program based on a general equilibrium search model. The results show that the ITC program leads to more employment opportunities than the PTC program. This finding is robust according to sensitivity analyses.