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Characteristics of Ultrasensitive Hexagonal-Cored Photonic Crystal Fiber for Hazardous Chemical Sensing
Get PDFThis research article was published by MDPI 2022A highly sensitive non-complex cored photonic crystal fiber sensor for hazardous chemical
sensing with water, ethanol, and benzene analytes has been proposed and is numerically analyzed
using a full-vector finite element method. The proposed fiber consists of a hexagonal core hole and
two cladding air hole rings, operating in the lower operating wavelength of 0.8 to 2.6 μm. It has been
shown that the structure has high relative sensitivity of 94.47% for water, 96.32% for ethanol and
99.63% for benzene, and low confinement losses of 7.31 × 10−9 dB/m for water, 3.70 × 10−10 dB/m
ethanol and 1.76 × 10−13 dB/m benzene. It also displays a high power fraction and almost flattened
chromatic dispersion. The results demonstrate the applicability of the proposed fiber design for
chemical sensing applications
Classifying Swahili Smishing Attacks for Mobile Money Users: A Machine-Learning Approach
Get PDFThis research article was published by IEEE Access 2022Due to the massive adoption of mobile money in Sub-Saharan countries, the global transaction
value of mobile money exceeded 3 billion by the end of 2022, and Sub-Saharan Africa contributes half of the daily transactions. SMS
(Short Message Service) phishing cost corporations and individuals millions of dollars annually. Spammers
use Smishing (SMS Phishing) messages to trick a mobile money user into sending electronic cash to an
unintended mobile wallet. Though Smishing is an incarnation of phishing, they differ in the information
available and attack strategy. As a result, detecting Smishing becomes difficult. Numerous models and
techniques to detect Smishing attacks have been introduced for high-resource languages, yet few target
low-resource languages such as Swahili. This study proposes a machine-learning based model to classify
Swahili Smishing text messages targeting mobile money users. Experimental results show a hybrid model of
Extratree classifier feature selection and Random Forest using TFIDF (Term Frequency Inverse Document
Frequency) vectorization yields the best model with an accuracy score of 99.86%. Results are measured
against a baseline Multinomial Naïve-Bayes model. In addition, comparison with a set of other classic
classifiers is also done. The model returns the lowest false positive and false negative of 2 and 4, respectively,
with a Log-Loss of 0.04. A Swahili dataset with 32259 messages is used for performance evaluation
Improved Resource Allocation Model for Reducing Interference Among Secondary Users in TV White Space for Broadband Services
Get PDFThis research article was published by IEEE Access 2022In recent years, the Television White Space has attracted the interest of many researchers due to
its propagation characteristics obtainable between 470MHz and 790MHz spectrum bands. However, aggre-
gate interference increase when secondary users in wireless network increase. Aggregate interference on the
side of Primary Users has been extensively scrutinized. Therefore, resource allocation (power and spectrum)
is crucial when designing the Television White Space network to avoid interferences from Secondary Users
to Primary Users and among Secondary Users themselves. This study proposes a resource allocation model
that uses joint power and spectrum hybrid Particle Swarm Optimization, Firefly, and Genetic algorithm for
reducing the aggregate interference among Secondary Users. The algorithm is integrated with the admission
control algorithm so that; there is a possibility of removing some of the Secondary Users in the network
whenever the Signal to Noise Ratio threshold for Secondary and Primary Users is not met. We considered an
infeasible system whereby all Secondary and Primary Users may not be supported simultaneously. Metrics
such as Primary User Signal-to-noise ratio, sum throughput, and secondary user signal-to-noise ratio less
than the threshold used to compare the performance of the proposed algorithm and the results show that
PSOFAGA with effective link gain ratio admission control has the best performance compared to particle
swarm optimization, genetic algorithm, firefly algorithm, and PSOFAGA algorith
A review on the trends of maize biofortification in alleviating hidden hunger in sub-Sahara Africa
Get PDFThis research article was published by Elservier B.V. in 2022Micronutrient deficiency is a major problem affecting many people in developing countries who solely depend on maize as their single source of calories. Vitamin A deficiency is one of the health problems associated with micronutrient deficiency. It is caused by insufficient intake of food rich in vitamin A among vulnerable groups leading to impaired growth, reduced life span, and economic losses among resource-poor families. Strategies such as vitamin A supplementation, food fortification, and diet diversification have been adapted to combat vitamin A deficiency (VAD). However, these approaches have benefited urban dwellers leaving rural residents with deficiency sufferings, as they lack access to these alternatives. Biofortification of maize by breeding with higher provitamin A content holds immense promise as a cost-effective and sustainable approach in alleviating VAD in sub-Saharan African maize consumers. Biofortified maize has a greater potential to alleviate vitamin A deficiency in these countries. Despite the existence of biofortification programs in Africa, there is little documentation on what has been conducted, challenges, and future of maize biofortification programs in Africa; this limits any strategic planning required to produce maize varieties rich in micronutrients, including vitamin A. Therefore, the present study is a detailed systematic review to highlight the past, present, and future success of provitamin A maize biofortification and its adoption challenges in sub-Sahara Africa as a strategy for combating vitamin A deficiency
Assessment of variation in marginal productivity value of water in paddy farming systems in times of water stress
Get PDFThis research article was published in Water Journal, Volume 14, 2022.Global projections show that increases in agriculture water productivity (AWP) by 30
and 60% in rain-fed and irrigated agriculture, respectively, are required to ensure food security in
the period 2000–2025. In sub-Saharan Africa, attempts to understand AWP has seen a lamping of
input values which paints an unrealistic picture of AWP. We employed the residual imputation
method to isolate the marginal productivity value of water in six paddy farming systems viz. the
conventional transplant and flooding system (CTFS), the system of rice intensification (SRI), and the
Kilombero Plantation Limited (KPL) mechanized system. Findings showed that AWP for rainfed
CTFS is 0.39 kg/m3 or 0.003 US/m3
), rainfed SRI
(0.68 kg/m3 or 0.08 US/m3
), rainfed KPL (0.33 kg/m3
or 0.05 US/m3
). This shows that rainfed systems
have good AWP, especially physical ones. We recommend a rollout of rainfed SRI to secure local
food security and downstream ecosystem services. In addition, groupings of farmers will assist
in optimizing resources, stabilizing markets, and prices for the better economic value of water
(US$/m3
). Adoption of SRI will require intensive demonstration that needs public financing. In
addition, revamping the KPL off-taker arrangement with small-holder farmers could also be a good
PPP anchor
Antimicrobial resistant coliforms across four poultry production systems in Arusha and Moshi, Tanzania
Get PDFThis research article was published in the PAMJ One Health, Volume 7, Article 4, 11 Jan 2022Introduction: resistance to antimicrobials poses a
threat to human and animal health. This study
aimed to determine the prevalence of resistant
coliforms in poultry cloacal samples collected from
different poultry systems in Arusha and Moshi
districts, Tanzania. Methods: ten administrative
wards were randomly chosen in Moshi and Arusha
urban districts, with a random selection of one
representative farm in each ward per production
system (extensive, semi-intensive, intensive, and
broiler systems). Per farm, 10 chickens were
sampled using cloacal swabs. Samples were tested
for the presence of coliforms using MacConkey agar
without or with tetracycline, ciprofloxacin,
ceftazidime, and Imipenem. R software was used
for data analysis. Results: of the 80 farms targeted,
samples were collected from 79 farms representing
a total of 746 samples, of which 648 (86.8%) had
coliforms corresponding to 74 of the 79 sampled
farms. There was no significant difference in the
overall prevalence of coliforms between Moshi
(86%) and Arusha districts (87%) (p=0.81). The
overall proportions of resistant coliforms in Arusha
and Moshi varied depending on each antimicrobial
type. The prevalence of coliforms resistant to
tetracycline (95%) across all farm types in both
districts was higher compared to ciprofloxacin
(72%), imipenem (71%), and ceftazidime (84%)
(p<0.0001). The median counts of coliform
resistance (in log cfu) ranged from 4 to 10, with no
significant distinctions between antimicrobial
types. Conclusion: there is a widespread presence of
antimicrobial resistant coliforms in poultry
production systems. High tetracycline resistance
was observed across all farm types in both districts
Hydrogeochemical Analysis of Water Quality Dynamics Under Anthropic Activities on the Southern Slopes of Mount Kilimanjaro, Tanzania
Get PDFThis research article was published in the Chemistry Africa volume 5, pages 1589–1610 (2022)Water quality management requires consideration of surface water and groundwater dynamics. This study utilizes hydrogeochemical and isotopic techniques to understand anthropic influences on surface and groundwater resources in the Kikafu–Weruweru–Karanga (KWK) watershed southern slopes of Mount Kilimanjaro. The KWK watershed had two distinct characteristics, i.e., the upper region (above 1000 m.a.m.s.l) with surface water and few groundwater features and the lower part (below 1000 m.a.m.s.l) characterized by most groundwater sources and rivers. Water sampling and analysis were done between July and August 2019; multivariate statistical analysis aided the understanding of analytical findings. The results revealed NaHCO3 enrichment and Mixed CaNaHCO3 water type. The groundwater chemistry is chiefly controlled by aquifer lithology rather than anthropic activities. Stable isotopes show recharge from both regional and local rainfall as traced from the shallow wells. The levels of anthropic pollution indicators such as nitrate, chloride, and sulfate in deep wells are generally low in groundwater than in shallow wells. Anthropic activities such as irrigation, wastewater discharges and severe water abstraction confirmed significant contaminant agents at the dynamic levels. Next to geogenic releases, anthropic pollution as well is affecting groundwater quality in the aquifer. The current findings call for improved monitoring of the groundwater sources to track any changes in quality since there is a potential evolution to an undesirable state for domestic uses
Access to Supportive Health Services for People with Physical Disabilities: A Case of Health Facilities in Singida Rural District, Tanzania
Get PDFThis research article was published by Scientific Research Publishing Inc, 2022Background: It is estimated that above one billion people (15%) of the world’s populations are living with disabilities. The poor and unfriendly infrastructure at health facilities is the core challenge for people with physical disabilities in accessing healthcare. This study aimed to explore at what extent the existing infrastructure and design of health facilities in Singida rural district, Tanzania supports people with physical disabilities to access healthcare. Methods: A cross sectional health facility-based assessment of all thirty-two functioning health facilities in the district was done between June and December 2020 using observational checklist and key informants’ interviews consist of measurement procedures of the architectural condition of health facilities. Observation checklist was designed based on standard of health facilities in Tanzania, national guideline for safe care standards for dispensaries, health centers and district hospital of 2014 and national guideline for water, sanitation and hygiene in healthcare facilities of 2017. Data were analyzed by SPSS-26 using descriptive statistics to obtain frequencies tables, percentage and figure. Qualitative data were analyzed by using NVivo-12 software. Results: The study revealed that there was no signage, entrance area, parking and toilets designated for people with physical disabilities in all health facilities. There was no special seat, examination table/bed and special weight scale for people with physical disabilities in all facilities. Also, the doors were not wide enough to support wheelchair user to maneuver in all health centers and dispensaries. In addition, door handles were not user friendly for wheelchair users. In fact, only the hospital and health centers had wheelchairs while 27 (96.4%) of all dispensaries had no wheelchairs. Furthermore, ramp and pathways were not available in all dispensaries. All health facilities had stairs but the challenge was most of the staircases had no floor located before the steps. Conclusion: The study revealed that the infrastructures in most healthcare facilities pose challenges to people with physical disabilities when they access healthcare services. These findings call for need of improving health facilities’ infrastructure to accommodate people with physical disabilities and this should be given a priority
Comparison of cone bioassay estimates at two laboratories with different Anopheles mosquitoes for quality assurance of pyrethroid insecticide-treated nets
Get PDFThis research article was published by Springer Nature, 2022ckground: Quality assurance (QA) of insecticide-treated nets (ITNs) delivered to malaria-endemic countries is con ducted by measuring physiochemical parameters, but not bioefcacy against malaria mosquitoes. This study explored
utility of cone bioassays for pre-delivery QA of pyrethroid ITNs to test the assumption that cone bioassays are consist ent across locations, mosquito strains, and laboratories.
Methods: Double-blinded bioassays were conducted on twenty unused pyrethroid ITNs of 4 brands (100 nets, 5
subsamples per net) that had been delivered for mass distribution in Papua New Guinea (PNG) having passed pre delivery inspections. Cone bioassays were performed on the same net pieces following World Health Organization
(WHO) guidelines at the PNG Institute of Medical Research (PNGIMR) using pyrethroid susceptible Anopheles farauti
sensu stricto (s.s.) and at Ifakara Health Institute (IHI), Tanzania using pyrethroid susceptible Anopheles gambiae s.s.
Additionally, WHO tunnel tests were conducted at IHI on ITNs that did not meet cone bioefcacy thresholds. Results
from IHI and PNGIMR were compared using Spearman’s Rank correlation, Bland–Altman (BA) analysis and analysis of
agreement. Literature review on the use of cone bioassays for unused pyrethroid ITNs testing was conducted.
Results: In cone bioassays, 13/20 nets (65%) at IHI and 8/20 (40%) at PNGIMR met WHO bioefcacy criteria. All
nets met WHO bioefcacy criteria on combined cone/tunnel tests at IHI. Results from IHI and PNGIMR correlated
on 60-min knockdown (KD60) (rs=0.6,p=0.002,n=20) and 24-h mortality (M24) (rs=0.9,p<0.0001,n=20) but BA
showed systematic bias between the results. Of the 5 nets with discrepant result between IHI and PNGIMR, three had
confdence intervals overlapping the 80% mortality threshold, with averages within 1–3% of the threshold. Including
these as a pass, the agreement between the results to predict ITN failure was good with kappa=0.79 (0.53–1.00) and
90% accuracy.
Conclusions: Based on these study fndings, the WHO cone bioassay is a reproducible bioassay for ITNs with>80%
M24, and for all ITNs provided inherent stochastic variation and systematic bias are accounted for. The literatur
Soils, Science and Community ActioN (SoilSCAN): a citizen science tool to empower community-led land management change in East Africa
Get PDFThis research article was published IOPscience, 2022Pastoralist communities worldwide face complex challenges regarding food and feed productivity. Primary production systems are under stress, nutritional choices are changing and the relationship between development and agriculture is undergoing profound transformation. Under increasing pressure from climate and land use change, East African agro-pastoral systems are approaching a tipping point in terms of land degradation. There is an urgent need for evidence-led sustainable land management interventions to reverse degradation of natural resources that support food and water security. A key barrier, however, is a lack of high spatial resolution soil health data wherein collecting such information for each individual community is beyond their means. In this context, we tested whether bridging such data gaps could be achieved through a coordinated programme at the boundary between participation and citizen science. Key outputs included a community-led trial of a hand-held soil scanner, which highlighted a range of positive benefits and practical challenges in using this technology in this context, with identification of some potential solutions; and a targeted soil organic matter and nutrient status dataset in a small catchment-based community setting. The results show that if the practical challenges can be resolved, use of portable soil scanner technology has the potential to fill key knowledge gaps and thereby improve resilience to the threat of land degradation through locally responsive farmer and community decision-making