The LEXSYS project

this paper, at the point where lemmas are associated with tree families: each lemma / family combination would have a separate probability. Carroll and Weir (1997) outline other alternative probabilistic models, some of which we also intend to investigate

Evaluation of LTAG parsing with supertag compaction

One of the biggest concerns that has been raised over the feasibility of using large-scale LTAGs in NLP is the amount of redundancy within a grammar¿s elementary tree set. This has led to various proposals on how best to represent grammars in a way that makes them compact and easily maintained (Vijay-Shanker and Schabes, 1992; Becker, 1993; Becker, 1994; Evans, Gazdar and Weir, 1995; Candito, 1996). Unfortunately, while this work can help to make the storage of grammars more efficient, it does nothing to prevent the problem reappearing when the grammar is processed by a parser and the complete set of trees is reproduced. In this paper we are concerned with an approach that addresses this problem of computational redundancy in the trees, and evaluate its effectiveness

LEXSYS: Architecture and Implication for Intelligent Agent systems

LEXSYS, (Legume Expert System) was a project conceived at IITA (International Institute of Tropical Agriculture) Ibadan Nigeria. It was initiated by the COMBS (Collaborative Group on Maize-Based Systems Research in the 1990. It was meant for a general framework for characterizing on-farm testing for technology design for sustainable cereal-based cropping system. LEXSYS is not a true expert system as the name would imply, but simply a user-friendly information system. This work is an attempt to give a formal representation of the existing system and then present areas where intelligent agent can be applied

Legume CHOICE - a participatory tool to fit multi-purpose legumes to appropriate niches in mixed crop-livestock farming systems

German Federal Ministry for Economic Cooperation and DevelopmentDeutsche Gesellschaft für Internationale Zusammenarbei

Expression of Trypanosoma brucei gambiense Antigens in Leishmania tarentolae. Potential for Use in Rapid Serodiagnostic Tests (RDTs)

The development of rapid serodiagnostic tests for sleeping sickness and other diseases caused by kinetoplastids relies on the affordable production of parasite-specific recombinant antigens. Here, we describe the production of recombinant antigens from Trypanosoma brucei gambiense (T.b. gambiense) in the related species Leishmania tarentolae (L. tarentolae), and compare their diagnostic sensitivity and specificity to native antigens currently used in diagnostic kits against a panel of human sera. A number of T.b. gambiense protein antigen candidates were chosen for recombinant expression in L. tarentolae based on current diagnostics in field use and recent findings on immunodiagnostic antigens found by proteomic profiling. In particular, the extracellular domains of invariant surface glycoprotein 65 (ISG65), variant surface glycoproteins VSG LiTat 1.3 and VSG LiTat 1.5 were fused with C-terminal histidine tags and expressed as soluble proteins in the medium of cultured, recombinant L. tarentolae. Using affinity chromatography, on average 10 mg/L of recombinant protein was purified from cultures and subsequently tested against a panel of sera from sleeping sickness patients from controls, i.e. persons without sleeping sickness living in HAT endemic countries. The evaluation on sera from 172 T.b. gambiense human African trypanosomiasis (HAT) patients and from 119 controls showed very high diagnostic potential of the two recombinant VSG and the rISG65 fragments with areas under the curve between 0.97 and 0.98 compared to 0.98 and 0.99 with native VSG LiTat 1.3 and VSG LiTat 1.5 (statistically not different). Evaluation on sera from 78 T.b. rhodesiense HAT patients and from 100 controls showed an acceptable diagnostic potential of rISG65 with an area under the curve of 0.83. These results indicate that a combination of these recombinant antigens has the potential to be used in next generation rapid serodiagnostic tests. In addition, the L. tarentolae expression system enables simple, cheap and efficient production of recombinant kinetoplatid proteins for use in diagnostic, vaccine and drug discovery research that does not rely on animal use to generate materials

Looking back and moving forward: 50 years of soil and soil fertility management research in sub-Saharan Africa

Article purchased; Published online: 02 Nov 2017Low and declining soil fertility has been recognized for a long time as a major impediment to intensifying agriculture in sub-Saharan Africa (SSA). Consequently, from the inception of international agricultural research, centres operating in SSA have had a research programme focusing on soil and soil fertility management, including the International Institute of Tropical Agriculture (IITA). The scope, content, and approaches of soil and soil fertility management research have changed over the past decades in response to lessons learnt and internal and external drivers and this paper uses IITA as a case study to document and analyse the consequences of strategic decisions taken on technology development, validation, and ultimately uptake by smallholder farmers in SSA. After an initial section describing the external environment within which soil and soil fertility management research is operating, various dimensions of this research area are covered: (i) ‘strategic research’, ‘Research for Development’, partnerships, and balancing acts, (ii) changing role of characterization due to the expansion in geographical scope and shift from soils to farms and livelihoods, (iii) technology development: changes in vision, content, and scale of intervention, (iv) technology validation and delivery to farming communities, and (v) impact and feedback to the technology development and validation process. Each of the above sections follows a chronological approach, covering the last five decades (from the late 1960s till today). The paper ends with a number of lessons learnt which could be considered for future initiatives aiming at developing and delivering improved soil and soil fertility management practices to smallholder farming communities in SSA

Grammar compaction and computation sharing in automaton-based parsing

Wide-coverage grammars in Lexicalised TreeAdjoining Grammar (ltag) and related formalisms are structurally complex, containing many hundreds of elementary trees. In the context of the development of a full-scale ltag-like grammar and parsing system, we have investigated the claim that because many of these trees have a great deal of structure in common, a parser that manipulates trees individually performs a considerable amount of redundant computation. This claim has been used to motivate a parsing technique that encodes trees as finite state automata and captures overlapping computation through automata minimization. Our preliminary results show that this technique leads to considerable computation sharing. 1 Introduction The paper presents work that forms part of the ongoing LexSys project 1 . Our overall aim is to bring together and test in practice a variety of current nlp techniques, including the organisation of grammars into inheritance hierarchies for compact representati..

Thin Surface Layer of Plasma Treated Polyethylene

This paper reports on the effect of argon plasma on the high density polyethylene surface. The aim is to alter the surface in a manner and scale resulting in a stronger metal/polymer valence. The specimens are exposed to the direct current discharge, the irradiation time and power being variables. Electron paramagnetic resonance and X-ray photoelectron spectroscopy (EPR and XPS, respectively) are employed to determine the plasma effect. The surface wettability is studied by goniometry. The plasma treatment leads to radical generation and activation of such agents as oxygen, thus the surface wettability is significantly increased. The evolution ofthe treated surface in different media is studied. The influence of an increased oxygen concentration and the storage medium on the concentration gradient within the surface monolayers is proved. The EPR data show a gradual and very slow decrease in the number of radicals present on the treated surface after 2000 h. Also evidence is given for partial dissolution of the treated surface in water.Представлены результаты изучения влияния плазмы аргона на поверхность полиэтилена высокой плотности. Целью исследования является изменение поверхности таким образом, чтобы увеличить валентность ме­талла/полимера. Образцы подвергали воз­действию разряда постоянного тока, при этом время воздействия и мощность являлись переменными величинами. Для опре­деления влияния плазмы использовали электронный парамагнитный резонанс (ЭПР) и фотоэлектронную рентгеновскую спектроскопию. Смачиваемость поверхнос­ти изучали с использованием гониометрии. Плазменная обработка ведет к образованию радикалов и активизации таких реагентов, как кислород и таким образом, значительно увеличивается смачиваемость поверхности. Исследована эволюция обработанной по­верхности в различных средах. Приведено подтверждение влияния повышенной кон­центрации кислорода и среды на градиент концентрации в поверхностных монослоях. Данные ЭПР свидетельствуют о постепен­ном и очень медленном уменьшении коли­чества радикалов на обработанной поверхности после 2000 ч. Приведены также дан­ные о частичном растворении обработанной поверхности в воде

Nematodes and Weeds Control Effects of Pueraria phaseoloides and Flemingia macrophylla Fallows on Establishment, Survival and Yield of Plantain

The yield of plantain (Musa spp., AAB Simmonds) declines sharply after 1–2 years of cropping in West and Central Africa, due mainly to weeds and nematodes. A trial was carried out from January 2002 to October 2005 under two land-use systems (LUS) comprising 4–5 year-old bush fallow, dominated by Chromolaena odorata (L.) R. M. King & H. Rob, and a 20 year-old secondary forest, in three villages in southern Cameroon, to assess the effectiveness of Pueraria phaseoloides and Flemingia macrophylla as planted fallows for weed suppression and reduction in nematode damage of the plantain root system, and determine the yield response of different plantain sucker types to the weed suppression and reduced nematode damage. In each LUS, the treatments were a factorial combination of three levels of fallow system and four levels of plantain sucker type arranged in a randomised complete block design. Total above-ground biomass production of P. phaseoloides was 7.45 Mg ha-1, 4.2 times higher than F. macrophylla (1.78 Mg ha-1; P Boiling water-treated “Essong” > Untreated “Essong”. P. phaseoloides produced significantly (P < 0.05) the highest plantain yield. There were no differences between the natural regrowth and F. macrophylla for all the plantain yield parameters. Sanitizing suckers (boiling and nursery-derived) increased actual yield and quantity of edible bunches by 35% and 26%, respectively, compared to the untreated. It was concluded that P. phaseoloides had the greatest positive effect on the growth and yield of plantain