85 research outputs found
Determinants of manual control of water hyacinth expansion over the Lake Tana, Ethiopia
Water hyacinth is an exotic freshwater weed damaging wetland resources over the Lake Tana basin, Ethiopia. Different measures, including manual labour and harvesting machinery are in use to reduce its damage and expansion. Yet, the invasion of the weed appears expanding its scope across the wetlands of the Lake. This paper presented the study made to identify determinant factors affecting manual control of water hyacinth expansion over the Lake wetlands. It tried to analyse the expansion trend of the water hyacinth and community efforts to control its extension. Data were gathered from questionnaire surveys, group discussions, interviews and field observations. Descriptive statistics and binary logistic regression were used for data analysis. The study revealed that the water hyacinth cover in the Lakeâs wetland increased from â€10, 000 ha in 2011 to over 50, 000 ha in 2017. Wetland terrain, water depth, food availability, farming time, employment and government support were found significantly influencing the manual control practices of households. Hence, government support must increase to motivate people involvement in manual weed removal campaigns. Micro-relief maps and floating boats need be readily available to help participants easily identify risky terrains and expand the physical weed removal into the deeper waters.Key Words: Water hyacinth, Invasive weeds, Manual control, Wetlands, Lake Tana, Ethiopi
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The Community Ecology of Herbivore Regulation in an Agroecosystem: Lessons from Complex Systems
AbstractWhether an ecological community is controlled from above or below remains a popular framework that continues generating interesting research questions and takes on especially important meaning in agroecosystems. We describe the regulation from above of three coffee herbivores, a leaf herbivore (the green coffee scale, Coccus viridis), a seed predator (the coffee berry borer, Hypothenemus hampei), and a plant pathogen (the coffee rust disease, caused by Hemelia vastatrix) by various natural enemies, emphasizing the remarkable complexity involved. We emphasize the intersection of this classical question of ecology with the burgeoning field of complex systems, including references to chaos, critical transitions, hysteresis, basin or boundary collision, and spatial self-organization, all aimed at the applied question of pest control in the coffee agroecosystem
Rate-Induced Transitions in Networked Complex Adaptive Systems: Exploring Dynamics and Management Implications Across Ecological, Social, and Socioecological Systems
Complex adaptive systems (CASs), from ecosystems to economies, are open
systems and inherently dependent on external conditions. While a system can
transition from one state to another based on the magnitude of change in
external conditions, the rate of change -- irrespective of magnitude -- may
also lead to system state changes due to a phenomenon known as a rate-induced
transition (RIT). This study presents a novel framework that captures RITs in
CASs through a local model and a network extension where each node contributes
to the structural adaptability of others. Our findings reveal how RITs occur at
a critical environmental change rate, with lower-degree nodes tipping first due
to fewer connections and reduced adaptive capacity. High-degree nodes tip later
as their adaptability sources (lower-degree nodes) collapse. This pattern
persists across various network structures. Our study calls for an extended
perspective when managing CASs, emphasizing the need to focus not only on
thresholds of external conditions but also the rate at which those conditions
change, particularly in the context of the collapse of surrounding systems that
contribute to the focal system's resilience. Our analytical method opens a path
to designing management policies that mitigate RIT impacts and enhance
resilience in ecological, social, and socioecological systems. These policies
could include controlling environmental change rates, fostering system
adaptability, implementing adaptive management strategies, and building
capacity and knowledge exchange. Our study contributes to the understanding of
RIT dynamics and informs effective management strategies for complex adaptive
systems in the face of rapid environmental change.Comment: 25 pages, 4 figures, 1 box, supplementary informatio
Secure and scalable deduplication of horizontally partitioned health data for privacy-preserving distributed statistical computation
Background
Techniques have been developed to compute statistics on distributed datasets without revealing private information except the statistical results. However, duplicate records in a distributed dataset may lead to incorrect statistical results. Therefore, to increase the accuracy of the statistical analysis of a distributed dataset, secure deduplication is an important preprocessing step.
Methods
We designed a secure protocol for the deduplication of horizontally partitioned datasets with deterministic record linkage algorithms. We provided a formal security analysis of the protocol in the presence of semi-honest adversaries. The protocol was implemented and deployed across three microbiology laboratories located in Norway, and we ran experiments on the datasets in which the number of records for each laboratory varied. Experiments were also performed on simulated microbiology datasets and data custodians connected through a local area network.
Results
The security analysis demonstrated that the protocol protects the privacy of individuals and data custodians under a semi-honest adversarial model. More precisely, the protocol remains secure with the collusion of up to Nâââ2 corrupt data custodians. The total runtime for the protocol scales linearly with the addition of data custodians and records. One million simulated records distributed across 20 data custodians were deduplicated within 45 s. The experimental results showed that the protocol is more efficient and scalable than previous protocols for the same problem.
Conclusions
The proposed deduplication protocol is efficient and scalable for practical uses while protecting the privacy of patients and data custodians
Field Attractants for Pachnoda interrupta Selected by Means of GC-EAD and Single Sensillum Screening
The sorghum chafer, Pachnoda interrupta Olivier (Coleoptera: Scarabaeidae: Cetoniinae), is a key pest on sorghum, Sorghum bicolor (L.) Moench (Poaceae), in Ethiopia. At present there is a lack of efficient control methods. Trapping shows promise for reduction of the pest population, but would benefit from the development of attractive lures. To find attractants that could be used for control of P. interrupta, either by mass trapping or by monitoring as part of integrated pest management, we screened headspace collections of sorghum and the highly attractive weed Abutilon figarianum Webb (Malvaceae) for antennal activity using gas chromatograph-coupled electroantennographic detection (GC-EAD). Compounds active in GC-EAD were identified by combined gas chromatography and mass spectrometry (GC-MS). Field trapping suggested that attraction is governed by a few influential compounds, rather than specific odor blends. Synthetic sorghum and abutilon odor blends were attractive, but neither blend outperformed the previously tested attractants eugenol and methyl salicylate, of which the latter also was part of the abutilon blend. The strong influence of single compounds led us to search for novel attractive compounds, and to investigate the role of individual olfactory receptor neurons (ORNs) in the perception of kairomones. We screened the response characteristics of ORNs to 82 putative kairomones in single sensillum recordings (SSR), and found a number of key ligand candidates for specific classes of ORNs. Out of these key ligand candidates, six previously untested compounds were selected for field trapping trials: anethole, benzaldehyde, racemic 2,3-butanediol, isoamyl alcohol, methyl benzoate and methyl octanoate. The compounds were selected on the basis that they activated different classes of ORNs, thus allowing us to test potential kairomones that activate large non-overlapping populations of the peripheral olfactory system, while avoiding redundant multiple activations of the same ORN type. Field trapping results revealed that racemic 2,3-butanediol is a powerful novel attractant for P. interrupta
Qualitative parameters of pearl millet silage ammoniated with urea, at different compaction densities
Share the Love: Parental Bias, Women Empowerment and Intergenerational Mobility
International audienc
Policies, delivery models, and lessons learned from integrating mental health and substance abuse services into primary health care in Ethiopia
The immunomodulatory effect of vitamin D in chickens is dose-dependent and influenced by calcium and phosphorus levels
Vitamin D requirement is estimated to be higher than recommended values for the first two weeks of a broiler chicken's life, and is heavily dependent on the concentrations of Ca and P in the diet. There are data indicating the beneficial effect of higher vitamin D levels on performance and overall health of the chickens. However, data on the role of higher vitamin D levels on the innate immune reswponse of chickens are limited. Therefore, in the current study, we examined the effect of higher doses of vitamin D supplementation on the innate immune response in broiler chickens receiving optimal or calcium (Ca) and phosphorus (P) deficient diets. Three hundred Ross-308 male broiler chicks were randomly allocated into 60 cages with 5 birds per cage in a 3 Ă 2 factorial design with three levels of vitamin D and two levels of Ca/P with each experimental diet fed to 10 cages (10 replicates). Quantitative reverse transcription PCR (n = 5) was used to assess Toll-like receptor (TLR2b and 4), cytokine/chemokine (IL-12, IFN-Îł, IL-10, IL-4, IL-13, IL-18, CxCLi2) and cathelicidin (CATH1, CATHB1, CATH3) transcription levels in peripheral blood mononuclear cells (PBMCs), spleen, and bursa of Fabricius. Vitamin D supplementation of the Ca and P deficient diet considerably augmented transcription of TLR2b, TLR4, CATH1, and CATHB1 and predominantly Th2 cytokines in spleen. Supplementation of the control diet with vitamin D downregulated TLR4 transcription, and dose-dependently increased CATH1, CATHB1, Th1, and Th2 cytokine transcription (Th2>Th1). All diets downregulated CATH3 transcription. In conclusion, vitamin D or its derivative 25-OH-D3 both have a robust immunomodulatory property with a more favorable Th2 response, while at the same time enhancing observed Th2 cytokine responses under both optimal and lower Ca and P inclusion levels in the diets of broiler chickens
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