Ethnobotany of Wild and Semi-Wild Edible Plants of Chelia District, West-Central Ethiopia

This study was aimed at carrying out ethnobotanical investigation of wild and semi-wild edible plants (WSWEPs) involving documentation and analysis of the associated indigenous knowledge in Chelia District, West-Central Ethiopia. Semi-structured interviewing, direct matrix ranking, focus group discussions (FGDs), and guided field walks with informants were employed to collect qualitative and quantitative data. A total of 58 WSWEPs species classified into 48 genera and 30 botanical families were documented. The Moraceae with five species (16.66%) and Asteraceae with four species (13.33%) were the most represented families with high number of wild edible plant species. However, Urtica simensis (Urticaceae) (74.3% of informants), Chionanthus mildbraedii (Oleaceae) (68.4% of informants), Carissa spinarum (Apocynaceae) (66.1% of informants) and Ficus sur (Moraceae) (65.3% of informants) were the highly cited wild food plants. Most of the WSWEP species were shrubs represented with 21 species (36.20%) followed by trees and herbs with 18 species each (31.03% each) and liana with one species (1.72%). About 13.33% of the WSWEPs of Chelia District were endemic to Ethiopia. The average number of WSWEPs reported by women was more than that reported by men, and similarly senior members of the community also reported significantly higher numbers of edible species than younger members (P<0.05). The key informants reported significantly higher mean number of edible species of WSWEPs than the general informants (P<0.05). Women (80.1 ±1.6%) and children (76.1 ±2.3%) were the major gatherers followed by men (13.2±2.4%) and all household members (12.9 ±1.3%). The majority of respondents (77.4 ±2.1%) reported that WSWEPs were consumed by all household members followed by women (23.1± 2.2%), elders (15.8 ±2.3%), children (19.4 ±1.6%) and men 8.2±2.1%). Most inhabitants predominantly consumed fruits (40%) and fresh leaves (17.5%) followed by shoots (12.5%). Based on multipurpose criteria, Cordia africana, Vepris dainellii and Chionanthus mildbraedii were the most commonly used multipurpose species. Forests were the major reservoirs contributing 19 species (18%) of WSWEPs followed by woodland and disturbed bushland adding 28 species (17%) and river banks contributing 26 species (16%). Our analysis also showed that agricultural expansion was identified as a major threat to WSWEPs followed by overgrazing and fuelwood collection in the study area. In light of our findings, we recommend further research on the possibility of adapting, growing and intentionally managing some of the commonly consumed WSWEPs as well as on the toxicity and nutritional composition of these plants to ensure safety of consumption and economic benefits

Work extremum principle: Structure and function of quantum heat engines

We consider a class of quantum heat engines consisting of two subsystems interacting via a unitary transformation and coupled to two separate baths at different temperatures $T_h > T_c$. The purpose of the engine is to extract work due to the temperature difference. Its dynamics is not restricted to the near equilibrium regime. The engine structure is determined by maximizing the extracted work under various constraints. When this maximization is carried out at finite power, the engine dynamics is described by well-defined temperatures and satisfies the local version of the second law. In addition, its efficiency is bounded from below by the Curzon-Ahlborn value $1-\sqrt{T_c/T_h}$ and from above by the Carnot value $1-(T_c/T_h)$. The latter is reached|at finite power|for a macroscopic engine, while the former is achieved in the equilibrium limit $T_h\to T_c$. When the work is maximized at a zero power, even a small (few-level) engine extracts work right at the Carnot efficiency.Comment: 16 pages, 5 figure

Antimicrobial activity of traditional medicinal plants from Ankober District, North Shewa Zone, Amhara Region, Ethiopia

Context: Traditional medicinal plants have long been used in Ethiopia to treat human and livestock ailments. Despite a well-documented rich tradition of medicinal plant use in the country, their direct antimicrobial effects are still poorly known. Objective: To investigate the antimicrobial activity of 19 medicinal plant species that were selected based on the ethnobotanical information on their traditional use to treat infectious diseases in Ankober District. Methods: About 23 different ethanol extracts of plants obtained by maceration of various parts of 19 medicinal plant species were studied for potential antimicrobial activity using a broth microdilution method against Bacillus cereus, Bacteroides fragilis, Candida albicans, Clostridium perfringens, Enterococcus faecalis, Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella enteritidis, Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pyogenes. Results: Plant extracts from Embelia schimperi Vatke (Myrsinaceae) showed the strongest antibacterial activity with a minimum inhibitory concentration (MIC) value of 64 mu g/ml against B. cereus, L. monocytogenes, and S. pyogenes. Growth inhibitory activities were also observed for extracts of Ocimum lamiifolium Hochst. (Lamiaceae) against S. pyogenes, and those of Rubus steudneri Schweinf. (Rosaceae) against S. epidermidis at an MIC value of 128 mu g/ml. Generally, 74% of ethanol extracts (17 extracts) showed antimicrobial activity against one or more of the microbial strains tested at an MIC value of 512 mu g/ml or below. Discussion and conclusions: Results confirm the antimicrobial role of traditional medicinal plants of Ankober and warrant further investigations on promising medicinal plant species so as to isolate and characterise chemicals responsible for the observed strong antimicrobial activities