Solving XCSP problems by using Gecode

Gecode is one of the most efficient libraries that can be used for constraint solving. However, using it requires dealing with C++ programming details. On the other hand several formats for representing constraint networks have been proposed. Among them, XCSP has been proposed as a format based on XML which allows us to represent constraints defined either extensionally or intensionally, permits global constraints and has been the standard format of the international competition of constraint satisfaction problems solvers. In this paper we present a plug-in for solving problems specified in XCSP by exploiting the Gecode solver. This is done by dynamically translating constraints into Gecode library calls, thus avoiding the need to interact with C++.Comment: 5 pages, http://ceur-ws.org/Vol-810 CILC 201

The political economy of regionalism: Regional integration arrangements and Africa\u27s development. COMESA in a comparative context

This thesis adopts a comparative approach to examine the role of the Common Market for Eastern and Southern Africa (COMESA) in the promotion of socio-economic and political development in Eastern and Southern Africa. The thesis begins by providing a theoretical background to the concept of regionalism. It then traces the emergence of regionalism within the political economy of the international system, beginning from the era of mercantilism to the era of globalization. It then provides a critical overview of the European Union (the EU), the North American Free Trade Agreement (NAFTA), the Common Market of the Southern Cone (MERCOSUR) and the Association of South East Asian Nations (ASEAN) and analyses the achievements of these regional integration arrangements in so far as meeting the socio-economic and political development needs of their respective regions is concerned and builds the framework within which COMESA is compared vis-a-vis these regional integration arrangements. (Abstract shortened by UMI.)Dept. of History, Philosophy, and Political Science. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2005 .M66. Source: Masters Abstracts International, Volume: 44-03, page: 1217. Thesis (M.A.)--University of Windsor (Canada), 2005

Impacts of agricultural trade and market liberalization of food security in developing countries: comparative study of Kenya and Zambia

The introduction of agricultural reforms has debatable effects on food security in developing countries. This research investigates how such effects influenced maize supply in two developing countries which were among the first to introduce agricultural reforms. Conclusions from the research suggest that agricultural reforms led to mixed results. This may be attributed to the sometimes stop-go nature of reform implementation. The mixed results are reflected in the weak maize output response to price changes. Overall country economic conditions, state of agricultural development can be attributed to the pace of response, hence effect on agricultural supply. Elasticity of maize output to changes in price and acreage are strongly significant in maize output for the case of Kenya. Both restricted models of maize production suggest that prior to the introduction of reforms acreage, prices and alternative crops were more elastic when simulated with Zambian data than with Kenyan data.food security, agricultural reforms, elasticity of supply, International Relations/Trade,

Characterization of a modified poly(propylene imine) dendrimer host system

The research in this dissertation focuses on the design of a novel redox-responsive host system that has the ability to encapsulate guest molecules. The host at hand is a tri(ethylene oxide), TEO, pyrrole-terminated PPI dendrimer that possesses water-solubility as a result of the presence of the TEO chains on the pyrrole groups and redox-responsive activity from the pyrrole groups after their oligomerization. The pyrrole moieties at the periphery of the dendrimer exhibit the ability to be oligomerized by oxidation chemistry, and this is shown to aid in the retention and egress of guest molecules located within the dendrimer interior. These studies were followed by Visible spectroscopy, in which various solvents and oxidizing agents were employed for the oligomerization of the pyrrole end groups. The synthesis of this dendrimer system employed many reaction types, including but not limited to, bromination, SN2, deprotection and protection, and coupling reactions. Three substitution of the pyrrole moiety with the TEO chain was necessary to allow the 2- and 5-positions to remain available for oligomerization. Three new three-substituted pyrrole molecules were synthesized in this work, along with 4 new pyrrole-modified PPI dendrimers, referred to as TPDx. Characterization of these TPD host systems consisted of light scattering studies of their aqueous and non-aqueous solutions, encapsulation/release of a hydrophobic guest by TPDx monitored with Vis and fluorescence spectroscopies, and TPDx oligomerization followed with UV-Vis-NIR and FT-IR spectroscopies. The light scattering studies revealed aggregation of the host molecules, which was dependent on many variables, including solvent system, TPDx concentration, and temperature. The ability of the pyrrole moieties on the dendrimer to remain redox-active was clearly demonstrated. The TPDx were treated with different oxidizing agents in various solvent systems, and as a result they were able to form intramolecular oligo(pyrrole) units around the periphery of the dendrimer. The TPDs also have the ability to trap guest molecules, namely Nile Red, in aqueous media within their interior regions through static and dynamic trapping mechanisms. The trapping of guests within the TPDs was determined to be time dependent and largely a function of the steric constraints at the periphery of the TPDs

An Enhanced Features Extractor for a Portfolio of Constraint Solvers

Recent research has shown that a single arbitrarily efficient solver can be significantly outperformed by a portfolio of possibly slower on-average solvers. The solver selection is usually done by means of (un)supervised learning techniques which exploit features extracted from the problem specification. In this paper we present an useful and flexible framework that is able to extract an extensive set of features from a Constraint (Satisfaction/Optimization) Problem defined in possibly different modeling languages: MiniZinc, FlatZinc or XCSP. We also report some empirical results showing that the performances that can be obtained using these features are effective and competitive with state of the art CSP portfolio techniques

Vegetational Change and Land Degradation in the Lake Baringo Area, Kenya, During the Late Holocene: Evidence from the Paleorecord and Remote Sensing

This dissertation investigates the history of vegetational changes and land degradation in the Lake Baringo area, Kenya, East Africa, during the Late Holocene. It uses 14C -and 210Pb-dated fossil pollen, fungal spores, microscopic charcoal, and stratigraphic record from lake-sediment cores to reconstruct the paleoenvironment in the East African region. More recent changes in the Lake Baringo are examined using remote sensing imagery. These data provide one the first high-resolution late Holocene pollen records from the semi-arid region of Kenya (and one of only a handful from East Africa in general). Lake Baringo records a sedimentation rate of 1 cm yr-1, which remained largely unchanged for both the prehistoric period, prior to European settlement in the Baringo ecosystem (AD 1890s), and after, including the present. That raised the possibility that background environmental conditions and not humans are the main drivers of land degradation in the ecosystem. A record from a 363-centimeter core retrieved from Lake Baringo reveals a largely dry environment that is punctuated by a succession of centennial- to decadal-scale wet and dry episodes, separated by rather sharp transitions, including two intense dry episodes at ca. AD 1650 and AD 1750 that led to drying of the lake. The two episodes are reflected by poor pollen preservation environment and by relatively high percentages of dry-indicator species such as Podocarpus, Olea, Euclea, Acacia, Balanitaceae, Gramineae, and Cyperaceae. However, climatic implications of the changes in pollen spectra in the Lake Baringo record are limited by the extremely high sedimentation rate in Lake Baringo that effectively constrains the chronological record of the cores to the last 300 14C yr BP. Satellite imagery analyzed in this dissertation reveals that deforestation and the resultant land degradation have contributed to increased sediment yield in the lake. Consequently, the lake surface area was reduced by over 10% and turbidity increased, which is confirmed by a statistically significant increase (t = -84.699, p \u3c0.001) in the albedo between 1986 and 2000. Although climatic variations account for some of the changes in the lake catchment most of the changes in land cover are inherently linked to mounting human and livestock population in the Lake Baringo catchment

Drop out among Pupils in Rural Primary Schools in Kenya: The Case of Nandi North District, Kenya

The role of education in socializing the individual to fit in the society cannot be gainsaid. This is because education empowers people to improve their well being and participation in nation building. But recent research has shown that the spate of school drop-out among primary school pupils is worrying. This is happening in Kenya despite the inception of Free Primary Education programme in 2003. Practically pupils’ drop out poses a serious threat to gains in education despite the Government’s emphasis on Education for All by the year 2015. In Nandi North District, the problem is more pronounced among the primary pupils. The study therefore was conceived as a result of the increased pupil dropout rate in public primary schools causing wastage and affecting curriculum implementation. The study sought to establish the causes of drop out among pupils and strategies that institutions of learning can adopt to address this problem.  The study adopted descriptive survey design. It targeted 6322 standard eight pupils, 2569 class teachers and 286 head teachers. Out of this target population, a sample size of 1970 standard eight pupils, 769 class teachers and 86 head teachers was selected. Data were collected using class teachers' and pupils' questionnaires and head teachers' interview guide to gather information on the causes of school dropout. Data were analyzed by use of descriptive statistics and the findings presented in form of figures and tables. The study findings indicated that teenage pregnancy, chronic repetition, family size, lack of motivation for schooling, parental negligence, influence from peers, lack of trained teacher counsellors and early marriages were the main causes of school dropout. It further pointed out that the factors leading to the dropout of girls are different from those for boys. The study therefore recommends that the government and other stakeholders should address the issue of school dropout rate and come up with measures to curb it to avoid wastage of school curriculum resources and facilities and above all, wastage of them would be future leaders full of discovery knowledge for this current era of information and technology. In addition, the government should strengthen policies on the expenditure of the FPE set aside to benefit all children for quality education. Keywords: Drop Out, Pupils, Rural Primary Schools, Kenya, Nandi North District, Kenya

Management of Business Challenges Among Small and Micro Enterprises in Nairobi-Kenya

Small and Micro Enterprises (SMEs) play an important economic role in many countries. In Kenya, for example the SME sector contributed over 50percent of new jobs created in 2005 but despite their significance, SMEs are faced with the threat of failure with past statistics indicating that three out five fail within the first few months. This study sought to understand how SMEs manage the challenges they face. These challenges seem to change (evolve) according to different macro and micro conditions. This study employed stratified random sampling to collect data from 198 businesses using interviews and questionnaires. The data was analysed descriptively and presented through figures, tables and percentages. The findings indicate that SMEs face the following challenges; competition among themselves and from large firms, lack of access to credit, cheap imports, insecurity and debt collection. Credit constraint seems to be easing up when compared to previous researches. Relevant training or education is positively related to business success. The SMEs have the following strategies to overcome the challenges; fair pricing, discounts and special offers, offering a variety of services and products, superior customer service and continuously improving quality of service delivery. The research concludes that business success is a consequence of embracing a mix of strategies

Una semantica distribuita per il Multi-CCS utilizzando reti di Petri

Questa tesi descrive e approfondisce l'algebra di processo Multi-CCS, le fornisce una semantica basata sulle reti di Petri non limitate - a correzione e miglioramento della precedente - e una dimostrazione dettagliata della sua correttezza, ovvero della bisimilitudine tra la marcatura ottenuta dalla uova semantica e da un generico processo Multi-CCS e lo stesso processo nella semantica di default definita sugli LT