Intervention analysis with state-space models to estimate discontinuities due to a survey redesign

An important quality aspect of official statistics produced by national statistical institutes is comparability over time. To maintain uninterrupted time series, surveys conducted by national statistical institutes are often kept unchanged as long as possible. To improve the quality or efficiency of a survey process, however, it remains inevitable to adjust methods or redesign this process from time to time. Adjustments in the survey process generally affect survey characteristics such as response bias and therefore have a systematic effect on the parameter estimates of a sample survey. Therefore, it is important that the effects of a survey redesign on the estimated series are explained and quantified. In this paper a structural time series model is applied to estimate discontinuities in series of the Dutch survey on social participation and environmental consciousness due to a redesign of the underlying survey process.Comment: Published in at http://dx.doi.org/10.1214/09-AOAS305 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Landscape level characterization of seasonal floodplains under community based aquaculture: illustrating a case of the Ganges and the Mekong Delta

The project 'Community-based Fish Culture in Seasonal Floodplains' (henceforward the community-based fish culture project), CGIAR Challenge Program on Water and Food, aims to enhance fish production in seasonal floodplains to improve and sustain rural livelihoods in Bangladesh, Cambodia, China, Mali and Vietnam. Based on the premise that production from these water bodies could be enhanced by stocking locally important fish species, the community-based fish culture project seeks to develop technologies and institutional arrangements to support collective fish culture in the flood season. The current report provides a landscape level characterization of seasonal floodplains in two of these areas. We compare the Ganges seasonal floodplain agro-ecology in Bangladesh to that in the Mekong Delta of Cambodia and Vietnam. In both areas the project has been under implementation since the outset, but has met with contrasting resultsFlood plains, Aquaculture, Remote sensing

The role of systemic inflammation and the apolipoprotein E gene in human immunodeficiency virus-associated cognitive impairment

Includes abstract. Includes bibliographical references

Gate Delay Fault Test Generation for Non-Scan Circuits

This article presents a technique for the extension of delay fault test pattern generation to synchronous sequential circuits without making use of scan techniques. The technique relies on the coupling of TDgen, a robust combinational test pattern generator for delay faults, and SEMILET, a sequential test pattern generator for several static fault models. The approach uses a forward propagation-backward justification technique: The test pattern generation is started at the fault location, and after successful ¿local¿ test generation fault effect propagation is performed and finally a synchronising sequence to the required state is computed. The algorithm is complete for a robust gate delay fault model, which means that for every testable fault a test will be generated, assuming sufficient time. Experimental results for the ISCAS'89 benchmarks are presented in this pape

GIS applications for poverty targeted aquaculture development in the lower Mekong Basin.

In the lower Mekong Basin, marginal socio-economic conditions prevail amongst rural small scale farming households which heavily depend on highly seasonal, rain-fed farming systems for their livelihood. Persistent rural poverty is aggravated by frequently occurring droughts and floods. A yearly flood-drought cycle, while essential to their household economy based on rice and fisheries, renders rural poor livelihoods vulnerable to recurrent periods of food insecurity. This research demonstrates how a combination of publicly accessible Remote Sensing imagery and disaggregated poverty maps, within a comprehensive rural development framework, can provide an effective method to target pro-poor aquaculture development interventions at the local level. An agro-ecosystems analysis is performed in order to capture the seasonal dynamics of water- and aquatic resource exploitation. A holistic farming systems approach emphasises the potential of ponds in integrated rural smallholder systems to reduce poverty and vulnerability under rain fed conditions. A Geographic Information System (GIS), an efficient spatial inventory tool and decision support system in resolving real world problems, is used to identify where rural poor households can potentially benefit from the integration of aquaculture into existing production systems. A time series of satellite derived vegetation index data reveals distinct agro-ecosystem seasonality over large parts of the study area, which is indicative for farming systems under rain fed conditions. The developed methodology is capable of identifying functionally different agro-ecosystems. Socio-economic indicators for Cambodian parts of the lowland areas point to widespread rural poverty and vulnerability to recurrent food insecurity, which is directly related to agro-ecosystems seasonality and annual climate variability. Dependence of farming households on low productivity rain fed rice agro-ecosystems in Cambodia’s southern provinces is in stark contrast to the highly productive farming systems directly bordering it, in the freshwater fluvial zone of the Vietnamese Mekong Delta. A rapid increase in rice productivity in this densely populated area went hand-in hand with a considerable reduction in rural poverty. In this flood-prone but fertile area, resource competition and falling market prices of rice may have prompted the development of a range of integrated farming systems. The incorporation of ponds on farm in these systems facilitates reuse of nutrients from farm by-products for low-input aquatic resource production. In Northeast Thailand, crop production and low-input aquaculture have been successfully integrated along a tradition of water- and living aquatic resources management in farmer managed systems under resource poor conditions. A spatially linked commune level rural development database for Sisaket province in Northeast Thailand provides a useful framework for planning of aquaculture development through systems that are appropriate and relevant to local socio-economic and agro-ecological conditions. It was concluded that the socio-economic and agro-ecological context of rural poverty in Southeast Cambodia offers scope for similar pathways to improve rural wellbeing and reduce vulnerability to poverty and food insecurity by integrating aquatic resources development in pond based systems as part of an interdisciplinary approach towards rural development

Impacts of technological interventions on fish production and biodiversity of seasonal floodplains in Bangladesh

The Community-based Fish Culture in Seasonal Floodplains and Irrigation Systems (CBFC) project is a five year research project supported by the Challenge Program on Water and Food (CPWF), with the aim of increasing productivity of seasonally occurring water bodies through aquaculture. The project has been implemented in Bangladesh, Cambodia, China, Mali and Vietnam, where technical and institutional options for community based aquaculture have been tested. The project began in 2005 and was completed in March 2010. The objective of the study was to determine the impacts of technological interventions in the floodplains on fish yield and biodiversity benefiting the poor fisher folk and other community people. Technological interventions for fish culture in the floodplains included (a) the installation of low-cost large meshed bamboo fencing at water inlet and outlet points, and setting of ring culverts for maintaining suitable levels of water for fish culture without hampering the production of rice in the upland areas of the floodplains (b) stocking of larger fingerlings at suitable stocking densities of endemic (rohu, catla, mrigal) and exotic (silver carp, bighead carp, common carp/mirror carp) species at 31-48 kg/ha (c) post stocking management; use of extra fencing during over flooding and mobile guarding using boats (d) harvesting management; regulations in harvest for certain period, use of multiple harvesting techniques. These interventions were carried out through CB participation with initial technological and financial support from the Challenge Program Project (CP35).Flood plains, Freshwater aquaculture