MODELLING OF THIN LAYER DRYING KINETICS OF COCOA BEANS DURING ARTIFICIAL AND NATURAL DRYING

Drying experiments were conducted using air-ventilated oven and sun dryer to simulate the artificial and natural drying processes of cocoa beans. The drying data were fitted with several published thin layer drying models. A new model was introduced which is a combination of the Page and two-term drying model. Selection of the best model was investigated by comparing the determination of coefficient (R2), reduced chi-square (2) and root mean square error (RMSE) between the experimental and predicted values. The results showed that the new model was found best described the artificial and natural drying kinetics of cocoa under the conditions tested

Method of constructing braid group representation and entanglement in a Yang-Baxter sysytem

In this paper we present reducible representation of the $n^{2}$ braid group representation which is constructed on the tensor product of n-dimensional spaces. By some combining methods we can construct more arbitrary $n^{2}$ dimensional braiding matrix S which satisfy the braid relations, and we get some useful braiding matrix S. By Yang-Baxteraition approach, we derive a $9\times9$ unitary $\breve{R}$ according to a $9\times9$ braiding S-matrix we have constructed. The entanglement properties of $\breve{R}$-matrix is investigated, and the arbitrary degree of entanglement for two-qutrit entangled states can be generated via $\breve{R}(\theta, \phi_{1},\phi_{2})$-matrix acting on the standard basis.Comment: 9 page

Spatial and Temporal Variation in Abundance of Anopheles (Diptera: Culicidae) in a Malaria Endemic Area in Papua New Guinea

Abundance of anophelines in 10 villages in the Wosera area of Papua New Guinea was monitored during 1990-1993. Of 85,197 anophelines collected in 1,276 paired indoor and outdoor landing catches, 40.4% were Anopheles koliensis Owen, 36.7% An. punctulatus Donitz, 14.3% Art. karwari (James), 4.9% An. farauti s.l. Laveran, 3.1% An. longirostris Brug, and 0.7% An. bancroftii Giles. Maps of average indoor biting rates were produced using a Bayesian conditional autoregressive model which allowed for heterogeneities in sampling effort over time and space. Differences in spatial distributions among species were observed among and within villages and were related to the distribution of larval habitats and vegetation. Abundance of An. punctulatus and An. koliensis decreased with distance from the main waterway and probably from a sago swamp forest at 6 villages in North Wosera. Abundance of An. punctulatus was associated negatively with those of An. farauti s.l., An. longirostris, and An. bancroftii. The latter 3 species also had relatively low ratios of indoor-to-outdoor biting rates, and earlier biting times than An. punctulatus. Human blood indices of at least 0.79 were observed for all species except An. bancroftii. Abundance of all 6 species was correlated temporally with recent rainfall, but An. koliensis, An. kanvari, and An. longirostris showed greater temporal variability than the other species. An. punctulatus and An. koliensis tended to occur together in time and space (index of association, I = 0.85). Weaker associations were seen between An. farauti s.l. and An. longirostris (I = 0.44) and An. koliensis and An. kanvari (I = 0.34). The most frequently collected species occurred together and were concentrated near the Amugu river; the remaining species tended to occur together but in different parts of the Wosera area. The importance of understanding ecological requirements of the different Anopheles vectors and their association with key household and landscape features are discussed in relation to malaria transmission and contro

Associations of peak shifts in age-prevalence for human malarias with bednet coverage

Effects of bednet coverage (C) on prevalence of malaria were analysed using data from 1990-1992 from 9 Papua New Guinean villages. Effects of coverage varied by age, resulting in a shift in age of peak prevalence from 4 · 7 (C = 0%) to 11 · 6 (C = 100%) years for Plasmodium falciparum, from 3 · 4 to 4 · 9 years for P. vivax and from 11 · 0 to 16 · 8 years for P. malariae. In small areas with no bednets the age distribution of P. falciparum parasitaemia was like that of a holoendemic area. Where coverage was complete the pattern corresponded to mesoendemicity. Thus, protracted use of bednets can result in profound changes in the endemicity of malaria even when coverage is incomplete and without insecticide treatment. Average entomological inoculation rates (EIRs) estimated from indoor landing rates on individuals without bednets were 35, 12 and 10 infectious bites per person per annum for P. Falciparum, P. vivax and P. malariae, respectively. Logistic regression analyses indicated that the EIR estimate for P. falciparum was related to prevalence of this species independently of effects of bednet coverage. However, the recent EIR still accounted for much less variation than did the bednets. A similar pattern was seen for P. malariae, while there were no significant relationships between the recent EIR and the parasite positivity for P. vivax. It is concluded that short-term variations in inoculation rate are not important determinants of parasite prevalence in this populatio

Malaria: how useful are clinical criteria for improving the diagnosis in a highly endemic area?

To assess the validity of clinical criteria, we investigated 2096 outpatients diagnosed as malaria cases by nurses at a rural health subcentre in a highly endemic area of Papua New Guinea. 73% of the children < 10 years old had a positive blood slide for any species of Plasmodium and 32% had ⩾ 10 000 P. falciparum parasites per μL. For adults the frequencies were 51% and 9%, respectively. Stepwise logistic regression identified spleen size, no cough, temperature, no chest indrawing, and normal stools as significant predictors for a positive blood slide in children; no cough and normal stools predicted a positive blood slide in adults. Fever, no cough, vomiting, and enlarged spleen were significant predictors for a P. falciparum parasitaemia ⩾ 10 000/μL in children; in adults the only predictor was vomiting. In children the association of no cough and enlarged spleen had the best predictive value for a positive blood slide, and a temperature ⩾ 38 °C had the best predictive value for a P. falciparum parasitaemia ⩾ 10 000 μL. In adults, no major symptom had a good predictive value for a positive blood slide but vomiting had the best predictive value for a P. falciparum parasitaemia ⩾ 10 000/μL. When microscopy is not available, these findings can help in areas of high endemicity to determine which patients with a history of fever are most likely to have malaria and, more importantly, for which patients another diagnosis should be strongly considere

Relationships between Plasmodium falciparum infection and morbidity in a highly endemic area

A total of 736 outpatients diagnosed as having malaria using clinical criteria at a health centre in a highly endemic area of Papua New Guinea were investigated parasitologically. Plasmodium falciparum-attributable fractions were determined using a logistic regression model to compare parasite densities in cases with those of healthy individuals in community surveys. Thirty-seven percent of presumptive cases were found to have raised P. falciparum parasitaemia. This corresponds to an average reporting rate for the population of 0·53 attributable episodes per annum. Whilst the maximum prevalence of parasitaemia in the community was in children aged 5-9 years, the maximum age-specific incidence of attributable cases at the outpatient clinic was 2 cases per annum in the 2- to 4-year-old age group. The procedure for estimating attributable fractions makes it possible to compare morbidity rates between age groups, and to examine how the relationship between morbidity risk and parasite density changes with age, without diagnosing individual episodes. The average tolerance of parasites in an age group was measured by considering the level of parasitaemia associated with a given risk of malaria-attributable morbidity. In contrast to anti-parasite immunity, tolerance of parasites declines with age since at parasite isodensity the probability of being symptomatic increases with ag