64 research outputs found
Characteristics of smallholder dairy farms by association rules mining based on apriori algorithm
This research article published International Journal of Society Systems Science (IJSSS), Vol. 11, No. 2, 2019Characteristics of smallholder dairy farmers across regions are highly similar. However, introduction of improved farm management practices and extension support can be effective if specific constraints are identified for each farm typology. So far, approaches used to formulate farm types and characterise farming systems are not tailored to studying hidden patterns from farm datasets. Using the apriori association rules mining algorithm, characteristics of four smallholder dairy farm types are studied. Applying the power of the ArulesViz package, frequent items were visualised. These visuals which display some hidden attributes, solidified understanding on the key determinants for change in the studied farm types. The hidden smallholder farm characteristics were identified in addition to those given by cluster analysis in preliminary studies. Characterising smallholder farm data by using association rules mining is recommended in order to understand such systems in terms of what/how the majority practice rather than basing on cluster averages
A Singular Function Algorithm for Packing the Protocol Description Unit Packet
A new sequential singular function algorithm for packing Protocol Description Unit packets in the Short Message Mobile Originated Point-to-Point service is proposed. The single function algorithm simplifies the Short Message Entities programming where ATtention Commands are used to link Switched on Mobile Stations with Service Centers. This is in mode 0 of the short message service transmission. This paper shows that by using, only one single string function, the âMidâ or âSubstringâ function, it is still possible and is simpler to encode all the metadata contained in the Transport Protocol Data Unit frame of the Submit Protocol Description Unit packet. Our results show that, this proposed algorithm, always outputs 100% perfectly accurate packets for any combination of header and user data payload submitted in hexadecimal octets or decimal semi-octet format. It is thus possible for programmers not only to manipulate the distinct fields of the header data but also to modify the metadata using that single function only
Co-precipitation synthesis of reduced graphene oxide/NiAl-layered double hydroxide hybrid and its application in flame retarding poly(methyl methacrylate)
A reduced graphene oxide/NiAl-layered double hydroxide (RGO-LDH) was synthesized through a simple co-precipitation route. NiAl-layered double hydroxide (NiAl-LDH) nanoparticles were homogeneously dispersed on the reduced graphene oxide (RGO) nanosheets, which were simultaneously reduced during the process. RGO-LDH exhibited three steps of weight loss, leaving high residue. RGO-LDH was then solution blended into poly(methyl methacrylate) (PMMA) to investigate its effect on reducing flammability of the composite. With the incorporation of RGO-LDH, the thermal stability of PMMA composite was improved. Moreover, RGO-LDH endowed PMMA with the largest reduction in the heat release rate, smoke production and CO production rate relative to RGO or NiAl-LDH alone. RGO-LDH could decrease the production of volatiles including hydrocarbons, carbonyl compounds and epoxy compounds from the PMMA composite. The improved flame retardancy was ascribed to the combined effect of the physical barrier of RGO and the catalytic carbonization of NiAl-LDH. Š 2013 Elsevier Ltd. All rights reserved
Leveraging peer-to-peer farmer learning to facilitate better strategies in smallholder dairy husbandry
This research article published by SAGE Journal, 2020Peer-to-peer learning paradigm is seldom used in studying how farmers can increase yield. In this article, agent-based modelling has been applied to study the chances of dairy farmers increasing annual milk yield by learning better farming strategies from each other. Two sets of strategies were considered; in one set (S), each farmer agent would possess a number of farming strategies based on their knowledge, and in a second set (S'), farmer agents would possess farming strategies that they have adopted from their peers. Regression models were used to determine litres of milk that could be produced whenever new strategies were applied. By using data from Ethiopia and Tanzania, 28 and 25 determinants for increase in milk yield were fitted for the two countries, respectively. There was a significant increase in average milk yield as the farmer agents interacted and updated their S'â from baseline data, average milk yield of 12.7âÂąâ4.89 and 13.62âÂąâ4.47 to simulated milk yield average of 17.57âÂąâ0.72 and 20.34âÂąâ1.16 for Tanzania and Ethiopia, respectively. The peer-to-peer learning approach details an inexpensive method manageable by the farmers themselves. Its implementation could range from physical farmer groups to online interactions
The Genetic Structure and History of Africans and African Americans.
Africa is the source of all modern humans, but characterization of genetic variation and of relationships among populations across the continent has been enigmatic. We studied 121 African populations, four African American populations, and 60 non-African populations for patterns of variation at 1327 nuclear microsatellite and insertion/deletion markers. We identified 14 ancestral population clusters in Africa that correlate with self-described ethnicity and shared cultural and/or linguistic properties. We observed high levels of mixed ancestry in most populations, reflecting historical migration events across the continent. Our data also provide evidence for shared ancestry among geographically diverse hunter-gatherer populations (Khoesan speakers and Pygmies). The ancestry of African Americans is predominantly from Niger-Kordofanian (approximately 71%), European (approximately 13%), and other African (approximately 8%) populations, although admixture levels varied considerably among individuals. This study helps tease apart the complex evolutionary history of Africans and African Americans, aiding both anthropological and genetic epidemiologic studies
Mechanism of enhancement of intumescent fire retardancy by metal acetates in polypropylene
The effects of cobalt acetate (CoAc), manganese acetate (MnAc), nickel acetate (NiAc) and zincacetate (ZnAc) as fire retardant additive in intumescent polypropylene (PP) formulations containing PP/ammonium polyphosphate (APP)/pentaerythritol (PER) are reported. The limiting oxygen index (LOI) and vertical burning (UL94) tests and cone calorimetry were used to quantify the enhancement. Environmental chamber rheometry, thermal gravimetric analysis and the morphology of the residual char were used to investigate the mechanism of enhancement. The incorporation of small quantities of metal acetates had a significant influence on the fire behaviour. As an example, 0.7 wt% MnAc improved the UL 94 rating of PP/APP+PER (mass ratio 100/25, with APP/PER=3/1) sample from V-2 to V-0, while 1 wt% MnAc reduced the peak heat release rate and the total heat release by 18% and 12% in the cone calorimeter. Rheological data, cone
calorimetry, and photographs of the residual char showed how the fire retardancy of the systems were affected by the melt viscosity, which depended on the loading of metal acetate. During thermal decomposition, the metal acetates promote the crosslinking of the polymer and the fire retardant, reinforcing the protective intumescent layer. While, the effect is most potent at the optimal metal loadings. At higher MnAc loadings, the benefit of a stronger char is overwhelmed
by the adverse effect of crosslinking on the transition char layer. Thus, this paper offers a new
insight into the mechanism of the intumescent fire retarded PP system
Preparação e avaliação de nanocompĂłsitos de poliestireno - hidrĂłxido duplo lamelar HDL de ZnAl â organofuncionalizado com laurato/palmitato
Drug resistance to sulphadoxine-pyrimethamine in Plasmodium falciparum malaria in Mlimba, Tanzania
BACKGROUND: Sulphadoxine-pyrimethamine (SP) has been and is currently used for treatment of uncomplicated Plasmodium falciparum malaria in many African countries. Nevertheless, the response of parasites to SP treatment has shown significant variation between individuals. METHODS: The genes for dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) were used as markers, to investigate parasite resistance to SP in 141 children aged less than 5 years. Parasite DNA was extracted by Chelex method from blood samples collected and preserved on filter papers. Subsequently, polymerase chain reaction (PCR) and restriction fragment length polymorphism (PCR-RFLP) were applied to detect the SP resistance-associated point mutations on dhfr and dhps. Commonly reported point mutations at codons 51, 59, 108 and 164 in the dhfr and codons 437, 540 and 581 in the dhps domains were examined. RESULTS: Children infected with parasites harbouring a range of single to quintuple dhfr/dhps mutations were erratically cured with SP. However, the quintuple dhfr/dhps mutant genotypes were mostly associated with treatment failures. High proportion of SP resistance-associated point mutations was detected in this study but the adequate clinical response (89.4%) observed clinically at day 14 of follow up reflects the role of semi-immunity protection and parasite clearance in the population. CONCLUSION: In monitoring drug resistance to SP, concurrent studies on possible confounding factors pertaining to development of resistance in falciparum malaria should be considered. The SP resistance potential detected in this study, cautions on its useful therapeutic life as an interim first-line drug against malaria in Tanzania and other malaria-endemic countries
Effect of Rare Earth Ions on the Properties of Composites Composed of Ethylene Vinyl Acetate Copolymer and Layered Double Hydroxides
BACKGROUND: The study on the rare earth (RE)-doped layered double hydroxides (LDHs) has received considerable attention due to their potential applications in catalysts. However, the use of RE-doped LDHs as polymer halogen-free flame retardants was seldom investigated. Furthermore, the effect of rare earth elements on the hydrophobicity of LDHs materials and the compatibility of LDHs/polymer composite has seldom been reported. METHODOLOGY/PRINCIPAL FINDINGS: The stearate sodium surface modified Ni-containing LDHs and RE-doped Ni-containing LDHs were rapidly synthesized by a coprecipitation method coupled with the microwave hydrothermal treatment. The influences of trace amounts of rare earth ions La, Ce and Nd on the amount of water molecules, the crystallinity, the morphology, the hydrophobicity of modified Ni-containing LDHs and the adsorption of modifier in the surface of LDHs were investigated by TGA, XRD, TEM, contact angle and IR, respectively. Moreover, the effects of the rare earth ions on the interfacial compatibility, the flame retardancy and the mechanical properties of ethylene vinyl acetate copolymer (EVA)/LDHs composites were also explored in detail. CONCLUSIONS/SIGNIFICANCE: S-Niâ.âMgAl-La displayed more uniform dispersion and better interfacial compatibility in EVA matrix compared with other LDHs. Furthermore, the S-Niâ.âMgAl-La/EVA composite showed the best fire retardancy and mechanical properties in all composites
- âŚ