Determinants of high vitamin A supplementation coverage among pre-school children in Mali: the National Nutrition Weeks experience

OBJECTIVES: To assess vitamin A supplementation (VAS) coverage of children aged 6-59 months and the factors that favour or limit this coverage during the National Nutrition Weeks in Mali. DESIGN: Cross-sectional study. Interviews about demographic factors and children's adherence to the vitamin A capsule distribution programme were conducted. Professionals' knowledge of vitamin A and various aspects related to the supplementation strategy were assessed. SETTING: Five regions out of the eight regions in the country, in addition to Bamako District. Three rural communes were selected in three regions to represent rural areas. SUBJECTS: Parents or caregivers of children under 5 years of age, health agents who participated in the weeks, and community and administrative leaders. RESULTS: At least 80% of the children received the supplement. More 'traditional' communication channels (town criers, friends and family members) appeared to be more effective in reaching the target groups than modern methods, i.e. radio and television. Mothers' possession of a radio (Pearson chi2 = 5.03; P = 0.025) and fathers' education (Pearson chi2 = 19.02; P < 0.001), possession of a radio (Pearson chi2 = 8.93; P = 0.003) and listening to it (Pearson chi2 = 7.62; P = 0.006) all appeared to be statistically and significantly associated with children's coverage. In multivariate logistic regression analysis, only the study site (urban/rural) (P = 0.004), 'traditional channels' (P = 0.02) and fathers' education (P = 0.04) were significantly associated with children's coverage. Knowledge about VAS was high among community and administrative leaders, and health professionals. The planning and implementation of activities at the district level were found to be good in general. CONCLUSION: National Nutrition Weeks provide a successful example of a periodic VAS strategy with high coverage among children aged 6-59 months in Mali. Campaigns aimed at informing and sensitising populations during the Nutrition Weeks should also target children's fathers.     

Structure of agricultural simulators: A philosophical view

Model building is as much an art as a science. We attempt in this paper to define modelling terminology and discuss major steps in model building, analysis and synthesis and the sequence in which they are commonly undertaken in agricultural simulation projects. Model building tends to be an iterative process, meaning that at any point in the sequence the model builder may return to a previous step. This illustrates one of the important steps of a successful simulation—the earlier steps are always subject to revision as additional information is obtained. For example, a review of data often causes some reformulation of the problem. This reformulation may involve only a change in problem emphasis, or it may result in complete restructuring. In dealing with complex systems, analysts sometimes find that the first definition of the problem needs later revisions because it included too many (or sometimes too few) factors to represent adequately the alternatives and, therefore, a return to design.Availability of data is always an important consideration and is part of the problem formulation step of model building. Model constants and parameters, as well as initial values for all variables, are derived from these data. In addition, model assumptions are based on available data, giving model predictions some level of credibility. Finally, data must be available for model validation studies. Therefore, as pointed out in this paper, data sources should be located and their adequacy evaluated early in the model building sequence.The programmer or analyst programming the model should size up the task as an initial step. The result is serious if the size or complexity of the job is underestimated and the model will probably never function as economically or as efficiently as it should. Programming language choices and computing systems available are a part of this task.Consideration of model results may not be the end product of the modelling effort. We stress in this paper that the model building process should be an inter-disciplinary effort, so that when the team considers model results, each member has some realisation of their derivation. It is entirely possible at this point that the team decides more detailed or different results are necessary and that the model building process returns to the beginning with new objectives in mind.We attempt to give a detailed and thorough discussion of the model building process as discussed above. However, we hope the process discussed in this paper will be taken only as a philosophical view and should not be treated as a method that automatically produces the creative thinking required to translate a complicated real-world agricultural system into a more compact and usable simulation model.     

Nitrogen fertilization and plant development of cotton as determined by nodes above white flower 1

Early maturation is very beneficial in successfully harvesting a high‐quality, high‐yielding cotton (Gossypium hirstum L.) crop. If harvest is delayed until inclement weather patterns are established, both yield and fiber quality may be lost. The objective of these studies was to determine the maturity differences that occur in cotton differentially fertilized with nitrogen (N). Field experiments with irrigated cotton were conducted in 1990 and 1991 in three locations to study the effects of soil applied N rates on cotton maturity as estimated by nodes above white flower (NAWF) measurements. The test sites and soils were a production field near Manila, AR, on a Dundee sandy loam (fine‐silty, mixed, thermic Aeric Ochraqualfs), the Southeast Branch Experiment Station (SEBES) near Rohwer, AR, on an Hebert silt loam (fine‐silty, mixed, thermic Aeric Ochraqualfs), and the Northeast Research and Extension Center (NEREC) near Keiser, AR, on a Sharkey silty clay (very fine, montmorillonitic, nonacid, thermic Vertic Haplaquepts). Criteria used as indicators of crop maturity and earliness in these studies were the time in days after planting (DAP) and the accumulated heat units (HU) for the crop to reach NAWF=5. Increasing N rates delayed maturity at SEBES both years and at Manila in 1991 but not at NEREC either year. Differences in maturity between N treatments of 168 and 224 kg N/ha were minimal at all locations both years. Smaller differences in time for the plants to achieve NAWF=5 were observed in the cotton grown at Manila in 1990 and at NEREC both years. The smaller differences at Manila are assumed to be due to high levels of residual N from previous crops. Early‐season vegetative growth was indicated by NAWF extrapolated to first flower (60 DAP or 945 HU). A trend of higher NAWF at the extrapolated first flower stage with increasing N rate was observed, but generally differences were minimal. The NAWF values at DAP=60 were lower in 1991 than in 1990 for all locations.     

Site-Specific Variability in the Chemical Diversity of the Antarctic Red Alga Plocamium cartilagineum

Plocamium cartilagineum is a common red alga on the benthos of Antarctica and can be a dominant understory species along the western Antarctic Peninsula. Algae from this region have been studied chemically, and like “P. cartilagineum” from other worldwide locations where it is common, it is rich in halogenated monoterpenes, some of which have been implicated as feeding deterrents toward sympatric algal predators. Secondary metabolites are highly variable in this alga, both qualitatively and quantitatively, leading us to probe individual plants to track the possible link of variability to genetic or other factors. Using cox1 and rbcL gene sequencing, we find that the Antarctic alga divides into two closely related phylogroups, but not species, each of which is further divided into one of five chemogroups. The chemogroups themselves, defined on the basis of Bray-Curtis similarity profiling of GC/QqQ chromatographic analyses, are largely site specific within a 10 km² area. Thus, on the limited geographical range of this analysis, P. cartilagineum displays only modest genetic radiation, but its secondary metabolome was found to have experienced more extensive radiation. Such metabogenomic divergence demonstrated on the larger geographical scale of the Antarctic Peninsula, or perhaps even continent-wide, may contribute to the discovery of cryptic speciation.     

Purification and characterization of a beta-glucosidase from Citrus sinensis var. Valencia fruit tissue

A preliminary survey demonstrated activity for alpha-D-glucosidase, alpha-D-mannosidase, alpha-L-arabinosidase, beta-D-glucosidase, beta-D-xylosidase, and beta-D-galactosidase in orange fruit flavedo and albedo tissue. alpha-L-Rhamnosidase was not detected. Subsequently, a beta-glucosidase was purified from mature fruit rag tissue (composed of intersegmental septa, squeezed juice sacs, and fruit core tissue) of Citrus sinensis var. Valencia. The beta-glucosidase exhibited low levels of activity against p-nitrophenyl-beta-D-fucopyranoside (13.5%) and p-nitrophenyl-alpha-D-glucopyranoside (7.0%), compared to its activity against p-nitrophenyl-beta-D-glucopyranoside (pNPG, 100%). The enzyme was purified by a combination of ion exchange (anion and cation) and gel filtration (Superdex and Toyopearl HW-55S) chromatography. It has an apparent molecular mass of 64 kDa by denaturing electrophoresis or 55 kDa by gel filtration chromatography (BioGel P-100). Hydrolysis of pNPG demonstrated a pH optimum between 4.5 and 5.5. At pH 5.0 the temperature optimum was 40 degrees C. At pH 5.0 and 40 degrees C the K(m) for pNPG was 0.1146 mM and it had a V(max) of 5.2792 nkatal x mg(-1) protein (katal = 0.06 International Units = the amount of enzyme that produces, under standard conditions, one micromol of product per min). Of the substrates tested, the enzyme was most active against the disaccharide cellobiose (1-->4), but was not active against p-nitrophenyl-beta-D-cellobioside. High levels of activity also were observed with the disaccharides laminaribiose (1-->3), gentiobiose (1-->6), and sophorose (1-->2). Activity greater than that observed with pNPG was obtained with the flavonoids hesperetin-7-glucoside and prunin (naringenin-7-glucoside), salicin, mandelonitrile-beta-D-glucoside (a cyanogenic substrate), and sinigrin (a glucosinolate). The enzyme was not active against amygdalin, coniferin, or limonin glucoside.     

Comparison of oil recovered from tea tree leaf by ethanol extraction and steam distillation

Two methods for the determination of oil and oil major components from tea tree (Melaleuca alternifolia) leaf are quantitatively compared. A microwave assisted ethanol extraction and a 2-h hydrodistillation technique were used on both dry and fresh leaf from a low and a high oil concentration tree. There was no significant difference between dry and fresh leaf. The distillation technique recovered 88% and 82% of the extractable oil for the low and high concentration material, respectively. For both samples this distilled oil was composed of lower absolute amounts of sesquiterpenoids and marginally lower amounts of monoterpenoids. Extending the distillation to 6 h increased the sesquiterpenoid recovery but this resulted in a reduction in both the absolute and relative amounts of the oxygenated monoterpenoids, terpinen-4-ol and 1,8-cineole.