Enhancing telecommunications service engineering with mobile agenttechnology and formal methods

In order to be competitive, telecommunications service providers need new technologies that facilitate the rapid introduction of validated services in a cost-effective manner. Service engineering is a new discipline in which the telecommunications sector addresses the technologies and engineering processes required for service creation. Concurrent with these studies the development of applications in the Internet shows a new way to design telecommunications services based on the mobile agent paradigm. This brings new concepts that fit the requirements of service engineering. Therefore merging the approaches enables improvement of the service creation process. We illustrate this by presenting a framework for the formal design of telecommunications services using mobile agent technology complemented with formal methods. The contribution of this work is twofold. First, it relies on the Reference Model of Open Distributed Processing (RM-ODP) and shows how to adapt its concepts to agent orientation. Second, it provides agent-based service designers with validation and verification tools to state the quality of their specifications     

Self-sufficiency policy and irrigated rice productivity in the Senegal River Valley

Senegal’s high dependence on rice imports exposes the country to international market shocks with concomitant serious risks for food security. Since 2011 and triggered by high international prices, several initiatives to upgrade the rice value chain have emerged in the private sector. However, the major constraint private investors are currently facing is the insufficient supply of Senegal River Valley (SRV) paddy rice, implying that investment in productivity is becoming vital for the continuation of their operations, which are currently running below their optimum. The Senegalese government is investing heavily in the national rice sector, with the ambitious objective of achieving self-sufficiency in the year 2015. However, the program focuses primarily on extension of the area grown rather than increased productivity. We provide econometric support for policy making by assessing the determinants of productivity and technical efficiency in irrigated rice production systems through a five-year panel dataset of small-scale irrigated rice farms in the SRV. We found that due to the exacerbation of biological and institutional constraints in the SRV, rice growers had difficulties in maintaining productivity of their land. These constraints prevented them from further intensification, jeopardizing the national objective of self-sufficiency. Farmers exhibited modest technical efficiency levels, suggesting that, in addition to the proposed intensification strategies, substantial efforts in extension services will be required in order to achieve the goal of self-sufficiency. Improved weed and bird control as well as technological, organizational and institutional improvements were identified as key factors for boosting productivity and technical efficiency and, hence, these are target areas needing attention by Senegalese farmers and policy makers in their quest for increased food security.     

Price transmission analysis using threshold models: an application to local rice markets in Benin and Mali

In most African countries, spatial dispersion of production and consumption often results in high transaction costs that prevent farmers from accessing markets and causes asymmetry in price transmission. The objective of this study was to provide the baseline information on local rice price transmission between paired producer and consumer markets in Benin and Mali. To achieve this, we used Enders and Siklos’s threshold models on monthly price series from 2000 to 2010 to examine the nature of price transmission between selected markets in the surplus zones and the nearest important consumption markets. The results for Benin indicated that price transmission between markets in the surplus zone and the consumption markets was asymmetric, probably because of the prevalence of high transaction costs. These results showed that increases in price in the surplus-zone market were more quickly transmitted to the consumer market than decreases in price. Conversely, the results for Mali indicated symmetric price transmission between the market in the surplus zone and the consumer market, suggesting the prevalence of lower transaction costs. These results highlight the need for policies aiming to lower transaction costs observed in selected local rice markets in Benin. Specific policies, such as investment in public infrastructure, e.g. roads, could promote the vertical integration of local rice production with marketing. This would be crucial to achieving rice farmers’ food security and hence their wellbeing.     

Comparative photo‐oxidation under natural and accelerated conditions of polypropylene nanocomposites produced by extrusion and injection molding

The photo‐oxidation behavior under natural and accelerated conditions of polypropylene/layered silicate nanocomposite is studied in this article. The nanocomposites are prepared via simple melt mixing (extrusion and injection molding). The structure obtained is very dependent on the preparation mode and the modified clay used; mostly, exfoliation structure is produced. The nanocomposites start their photo‐degradation earlier than the control samples polypropylene and polypropylene‐graft‐maleic anhydride with a higher oxidation rate for specimen produced by injection molding. This is explained by the presence of organiphilic‐modified montmorillonite layers that trap the oxygen, increasing the oxygen pressure in the bulk and leading to a decrease of the induction period. Contrary to the control samples that display auto acceleration in their oxidation kinetics, the nanocomposites show a slight tendency to a plateau indicating a slowing down of the photo‐oxidation process. This is ascribed to oxygen starvation that occurs in the nanocomposite. The acceleration factor is found to be higher for the nanocomposite comparatively of the control samples. With the aid of SF₄ and NO treatments, the mechanism of photo degradation was found to be similar in PPgMA and its nanocomposites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Human IgE responses to rSm22.6 are associated with infection intensity rather than age per se, in a recently established focus of Schistomiasis mansoni

In studies of schistosomasis mansoni-endemic communities, individuals with IgE responses to a 22 kD adult worm antigen (rSm22.6) suffered lower intensities of reinfection after treatment. It is of interest to define the factors that lead to the production of rSm22.6-specific IgE because it is a marker for resistant individuals and it may be involved in the development of resistance to reinfection. In endemic populations rSm22.6-specific IgE increases linearly with age. However, it is not possible to distinguish between age per se and 'history of infection' in endemic populations because individuals are exposed to the parasite at an early age. We have, therefore, quantified pre- and post-treatment isotype responses to rSm22.6 in a comparatively 'epidemic' Senegalese community where the patients were infected at different ages and where pre-treatment intensity of infection can be taken as a reasonable measure of antigen exposure. Post-treatment isotype responses to rSm22.6 correlated positively with pre-treatment intensities of infection but were not shown to be related to age. IgG1, IgG4 and IgE responses to rSm22.6 were significantly higher after treatment with the difference increasing with the pre-treatment level of infection. These results from a recently established focus of infection suggest that isotype responses to rSm22.6 are antigen-exposure dependent rather than dependent on age per se.     

On the NiMoO4 oxidative dehydrogenation of propane to propene: some physical correlations with the catalytic activity

The - and -phases of NiMoO₄ have been investigated with different techniques (X-ray diffraction, electrical conductivity, IR spectroscopy) in order to tentatively rationalise the different catalytic activities observed in the oxidative dehydrogenation of propane to propene. XRD analyses have shown that at 595 ° C, the -phase is already present but a temperature of 700 ° C is required to obtain a full conversion into a pure -phase. Electrical conductivity showed the presence of anionic vacancies. It is proposed that propene is formed by the reaction of propane with surface O^2- anions. The -phase is almost twice more selective in propene formation than the -phase for comparable conversion at identical temperatures. This could derive from different oxygen environments on the active catalytic site.     

Crops that feed the world 7: Rice

Fears about global food security led to a spike in food prices in 2008, social unrest and pushed a further 100 million people into poverty. Prices remain high and volatile. In this paper we take a closer look at rice, a crop that feeds billions of people in the world, and focus in particular on Asia and Africa. On both continents, rice is grown in a wide range of climatic conditions, from river deltas to mountainous regions. Irrigated systems dominate in Asia and rainfed systems in Africa. Predicted demands for rice remain strong. An additional 116 million tons of rice will be needed by 2035 to feed growing populations. In Africa, where rice is the most rapidly growing food source, about 30 million tons more rice will be needed by 2035, representing an increase of 130% in rice consumption from 2010. About one-third of this extra rice will be needed in Nigeria alone. In Asia, per capita consumption of rice may go down in some mid- and high-income countries. Rice farming will need to produce about 8–10 million tons more paddy per year over the next decade. Without area expansion this will require an annual yield increase of about 1.2–1.5%, equivalent to an average yield increase of 0.6 t ha⁻¹ world-wide. Improving global food security will, therefore, necessitate concerted efforts to increase the productivity of rice per unit of land, water and/or labor in Asia and Africa, and the development of new land and water resources in a responsible and equitable manner to counteract losses due to urbanization and industrialization. During 2007–2011, productivity increases in Africa have been leading the way, with paddy rice production levels increasing by 9.5% per year, compared to 1.6% in Asia. Priorities for rice sector development include (i) continued and increased research efforts to close yield gaps and raise yield ceilings across rice growing environments through varietal development and improved rice production methods, and coping with climate change in both continents and (ii) strengthened and equitable public-private sector partnerships and conducive policy environments in Africa, with special emphasis on mechanization of rice farming from land preparation to harvest and rice processing practices.     

Control of shallow water and sediment continuity coupled system

This paper presents an algebraic method to design a linear feedback control for regulating the water flow in open channels. We deal with a hyperbolic system of partial differential equations describing the behavior of the water flow and the sediment transport. By using an a priori estimation techniques and the Faedo–Galerkin method, we build a stabilizing boundary control. This control law ensures a decrease of the energy and convergence of the controlled system.     

Weed management in upland rice in sub-Saharan Africa: impact on labor and crop productivity

Rice is one of the most important crops for food security in sub-Saharan Africa (SSA). There exists, however, a widening gap between its regional demand and supply. Competition from weeds is typically one of the major biophysical constraints in upland rice, frequently leading to significant yield losses and sometimes to complete crop failure, thereby threatening the food security of subsistence farmers. However, weed management practices that are currently employed to avoid such losses are associated with high weeding labor demands. This study examined the relationships between weeding times per farm, average time per hectare per weeding and rice yields of upland rice farmers in SSA, with the objective of estimating the impact of weeds on rural households’ economies in SSA reliant on upland rice production systems. To this end, we analyzed survey data collected from 992 farmers in four countries (Cameroon, Democratic Republic of Congo, Togo and Uganda). The counterfactual outcomes framework of modern evaluation theory was used to estimate the Average Treatment Effect (ATE) of the number of times a farm is weeded on weeding labor efficiency, as measured by the average number of hours spent per hectare at each weeding, and on crop productivity expressed as rice grain yield per hectare. A single weeding required 173 h per hectare, while weeding twice required 130 h per hectare per weeding (259 h per hectare in total) and weeding three times required 125 h per hectare per weeding (376 h per hectare in total). Correspondingly, a single weeding was associated with an average rice yield of 1.2 t ha^?1, weeding twice yielded 1.7 t ha^?1 and weeding three times yielded 2.2 t ha^?1. Compared to the situation where the farm is weeded only once and controlling for other factors, the model estimated yield gains of a second weeding to be 0.33 t ha^?1 and a third weeding to result in a gain of 0.51 t ha^?1. The estimated labor gains were respectively 64.2 and 68.1 h per hectare per weeding for a second and a third weeding. We conclude that weeding an upland rice crop more than once in SSA increases weeding labor efficiency by about 37 % and rice productivity by more than 27 %. Rather than motivating farmers to increase their labor inputs for manual weeding, however, we propose that more research and development funds should be devoted to developing, testing and promoting locally adapted strategies of labor-saving weed management in rice in sub-Saharan Africa. This will result in a significant contribution to regional food security and poverty alleviation.     

Economic analysis of consumer choices based on rice attributes in the food markets of West Africa—the case of Benin

The focus of this study was to investigate consumer preferences for various attributes of rice marketed in Benin. Consumer choice theory postulates that products are consumed not for themselves, but for the characteristics they possess that satisfy consumers’ greater liking of one attribute over another. In the case of rice, quality attributes, as incentives for both producers and consumers, have important price implications. In this study, we empirically analyzed the relationship between the price paid by consumers for their choice of rice and its attributes in the markets of Benin using hedonic pricing and discrete choice models of demand. We used data collected from rice-consuming households in four major provinces of Benin, in both rural and urban areas, during 2006. The results of this econometric estimation indicated that there was considerable variability in consumer preferences for different rice attributes across the regions studied. Nevertheless, consumers paid a premium price for observable attributes, such as grain size and breakage. In addition, both urban and rural consumers preferred imported and parboiled rice to domestic and raw rice. The study results showed that implicit prices paid by consumers for both domestic and imported rice were based on quality attributes. These findings have important implications for future breeding programs aimed at making domestic rice more competitive with imported rice.