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We use a dynamic international trade model to analyse the implications of international trade for agents’ preferences and economic growth. This model is based on the home market effect with external habit formation (“catching up with the Joneses”) and “learning by doing” in production. We demonstrate the following: the historical composition of consumption in countries determines industrialization after trade; the preferences of agents converge after trade, independent of the economic results; and the welfare effects of trade may be positive or negative depending on trading partner characteristics. In some scenarios, autarky is strictly preferred to trade. Thus, international trade does not necessarily imply greater welfare, as is the typical result in a static context under CES preferences.

Water management by the impoundment of reservoirs has been found to influence evapotranspiration not only locally but also at the basin scale. Highly regulated hydrological basins generally show the effect of a net increase in evapotranspiration accompanying the successive impoundment of reservoirs. However, understanding and isolating the effect from a particular single impounded reservoir remains a challenge due to the lack of long-term observation data required and the existence of many other drivers present at the basin scale. Focusing on the hydrological basin having the largest hydropower potential in China, we isolated in time and space and quantified the effects of a single impounded reservoir on evapotranspiration and the evaporative ratio (i.e., the ratio of actual evapotranspiration to precipitation) before and after the construction of the Ertan Dam in 1998. We find that the dam has increased evapotranspiration in the smallest subbasin by 46±15 mm/yr and the evaporative ratio by 0.05±0.015, from the period before impoundment (1983-1997) to that after impoundment (2000-2012). This increase is found only within the smallest differential subbasin holding the impounded reservoir and cannot be explained by other changes in land use or vegetation. We use this result from our hydrological basin-constrained approach to calculate the water footprint of the hydroelectric project as 16.5 m3/GJ, which accounts for additional hydroclimatic effects of the impoundment of the reservoir beyond the water surface. Hence, this study finds that when runoff data is available, the water consumption and the water footprint of hydropower projects can be calculated by water mass balance at the scale of their hydrological basins.

We study the single machine preemptive scheduling problem with both regular and overtime modes.The objective is to minimize the total tardiness and overtime costs.We propose a heuristic solution methodology for the problem.The efficiency of the heuristic is tested with upper bounds generated by the mathematical model. This paper studies the scheduling of a finite set of jobs on a single resource that operates under both regular and overtime capacity modes. Jobs, which can be preempted, have associated release and due dates. Limited overtime capacity can be utilized to reduce tardiness. However, since overtime is costly, justification of the overtime use depends on the trade-off between the tardiness and the overtime costs. The overall objective is to minimize the total cost of tardiness and overtime. To achieve this objective, we develop a holistic method composed of three-stages. We first provide a heuristic based on an effective priority rule for the base case where no overtime capacity is considered. This heuristic is later employed in the first-stage to produce a compact non-delay schedule built based on the assumption that overtime capacity incurs no additional cost. In the second stage, the overtime usage is reduced by shifting workload and generating a full-delay schedule without altering the tardiness of jobs produced in the first stage. The third stage improves the total costs by altering the tardiness of jobs in return for savings in overtime utilization. Using computational tests, we compare the performance of our heuristics to the upper bounds generated by the exact mixed-integer programming formulation. The results show that the proposed method is efficient in obtaining solutions that are considerably better than the generated upper bounds in significantly short times and as such, it can be quite useful as an effective solution approach especially for large size problems.

In this paper, an adaptive control scheme for maximum power point tracking of stand-alone PMSG wind turbine systems (WTS) is presented. A novel procedure to estimate the wind speed is derived. To achieve this, a neural network identifier (NNI) is designed in order to approximate the mechanical torque of the WTS. With this information, the wind speed is calculated based on the optimal mechanical torque point. The NNI approximates in real-time the mechanical torque signal and it does not need off-line training to get its optimal parameter values. In this way, it can really approximates any mechanical torque value with good accuracy. In order to regulate the rotor speed to the optimal speed value, a block-backstepping controller is derived. Uniform asymptotic stability of the tracking error origin is proved using Lyapunov arguments. Numerical simulations and comparisons with a standard passivity based controller are made in order to show the good performance of the proposed adaptive scheme.

Summary During the 20th century, Sweden underwent a persistent agricultural development. In this study, we use and combine historical hydroclimatic and agricultural data to investigate how this large scale change of land use, and subsequent intensification of crop production, affected regional hydrology in two adjacent Swedish drainage basins. We find a main increase of evapotranspiration (ET) as cultivated area and/or crop production increased during the period 1901–1940. Thereafter, ET stabilized at a new higher level. Comparison between the data given, water balance constrained ET quantification (ET wb ), and a range of different comparative estimates of purely climate driven ET (ET clim ) shows that only 31% of the steep 1901–1940 increase of ET wb can be explained by climate change alone. The remaining 69% of this ET wb shift, which occurred in both investigated drainage basins, is instead explainable to large degree by the regional land use conversion from seminatural grasslands to cultivated land and associated enhanced productivity of herbaceous species.

Este estudio examina el desempeño de fondos de pensiones obligatorios y voluntarios en el periodo 2004-2008. El documento presenta una metodología fundamentada en la técnica de componentes principales que facilita el proceso de selección de fondos. También se analizan dos metodologías de optimización de portafolios para evaluar mejoras en el desempeño en un periodo de evaluación, la primera sugerida por Markowitz (1952) y la segunda sugerida por Revéiz y Leon (2008b). Aplicando diferentes metodologías, se evidenció un incremento en el nivel de riesgo de los fondos obligatorios y voluntarios colombianos. Se halló además un conjunto de fondos que caracterizan adecuadamente el movimiento común de los retornos de los fondos. No se encontraron ganancias significativas en términos económicos ni estadísticos al utilizar una metodología de optimización en particular. This study examines performance of mandatory and voluntary pension funds in the 2004 – 2008 period. Furthermore, we present a methodology based on principal components that can aid affiliates when selecting funds. Moreover, we examine two portfolio optimization methodologies to evaluate any performance improvements in an evaluation period when choosing a particular methodology. The first one suggested by Markowitz (1952) and the second by Reveiz and Leon (2008b). We find an increase in risk, using several metrics, of mandatory and voluntary pension funds as well as a set of funds that better characterize the common movement of funds’ returns. No evidence was found in regards to economically or statistically significant gains of applying either optimization methodology using several holding periods.

Market orientation has emerged as a significant antecedent of performance and is presumed to contribute to long-term success. To investigate the impact of this predictor, a meta-analysis was conducted and findings suggest that the relationship between market orientation and business performance is positive and consistent worldwide. One of the unique contributions of this research is a sample that includes studies conducted in 23 countries spanning five continents. The moderating effects of business objective (profit, not-for-profit), industry type (manufacturing, service), socioeconomic development [gross domestic product (GDP) per capita, Human Development Index (HDI)), and Hofstede’s individualism cultural dimension] are examined. Stronger correlations between market orientation and business performance were found for not-for-profit compared to profit firms and service compared to manufacturing firms. D 2004 Elsevier B.V. All rights reserved.

1. 1. Acute effects of Karwinskia humboldtiana (Kh) were studied in some renal functions and structural patterns of renal tissue. 2. 2. Haemodinamic changes were observed with decrements of the glomerular filtration rate, renal plasma flow and filtration fraction during acute intoxication. 3. 3. A marked increment in the fractional excretion of sodium was observed in the rats treated with tullidora fruits ( Kh ). 4. 4. Cloudy swelling and hydropic degeneration was seen 72 hr after intoxication, mainly in the proximal convoluted tubules.