242 research outputs found

    Impact of Rubber Farming on the Socio-Economic Status of Households of Smallholders: A Descriptive Analysis

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    Rubber farming in Moneragala District has been introduced to enhance the socio-economic status of households of smallholders. Four focus group discussions and six qualitative case studies were conducted to assess the impact of rubber farming on their household level in 2020. Rubber smallholders were selected for the focus group discussions, using stratified random sampling technique and each discussion was comprised of twelve rubber smallholders. Data was collected using interview criteria which was developed and evaluated prior to its use with the expert team. The rubber smallholders were asked a series of semi-structured questions according to the interview guide by the researcher until theoretical saturation is obtained. Then a set of codes and categories were developed according to the grounded theory approach. Qualitative case studies were carried out with six rubber smallholders who were randomly selected from different land categories. A structured direct interview schedule was used in gathering data from rubber smallholders according to eleven criteria which were developed in collaboration with the expert team. It was highlighted that continuous household income from rubber farming has contributed to meet the expenses of education of children, medicine, food, purchasing agricultural and non-agricultural vehicles and renovation of living house with sustainable household income and regional development in Moneragala. In addition, it has generated new employment opportunities and new source of income for other labourers. Hence, expansion of rubber farming into non-traditional rubber growing areas in the country can be recommended in order to improve the socio-economic status of smallholders.     DOI: http://doi.org/10.31357/fhss/vjhss.v08i02.0

    SURVIVAL AND GROWTH OF MAHOGANY SEEDLINGS UNDER A NURSE CROP WITH DIFFERENT CANOPY OPENINGS

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    Swieicnia nuurophvl!« King is one of thc luxury class timbers of thc world, The survivaland growth of S, ntarcrophvlla when planted under the nurse crop, Atacia auriculifonniswith different canopy openings was determined. The study was carried out in a 9 year oldAcaci« plantation established by the Forest Department on a degraded. hilly land atNauiyapana ill Kcg.illc. Two experimental blocks (replicates) about I km apart wereselected for the study. In each block 3 plots (.'ix5 m) were selected on the basis or canopyopenings (open. moderate, closed) hy removal of trees and branches. Within each plot IXmahogany seedlings were planted. The photosynthetically active radiation at each canopyopening was measured using a data logger with PAR light sensors. The mean survivallevel of seedlings was found to be X3% (open gap-6FJ,; PAR). l)7'/r; (moderate gap-43%PAR) and 94% (closed gap- 24'!i; PAR). Height of seedlings measured monthly indicatedan increase in height with high light intensity. Similarly. the root collar diametermeasured 9 months after planting varied from 1.2 em (open canopy). O.9R em (moderatecanopy) to n,71 em (closed canopy). The mean number of leaves per plant under opencanopy was 15. and II under moderate and closed canopy. Data obtained so tnr indicatethat survival is low under open canopy with high light intensity, while growth is betterunder open canopy inferring that shade is important only during the initial establishmentphase of seedlings and not thereafter. However. there arc reports of high damage by themahogany shoot borer (/l\'jJsifi.\'/a roIJ/l.\'IO Moore) when grown in the open.

    Kandyan home gardens: Faunal repositories in Sri Lanka.

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    Kandyan home gardens are one of the major designs of sustainable land use systems that have evolved over hundreds of years incorporating high biodiversity and providing a diverse and stable supply of socio-economic products and service benefits to householders in Sri Lanka. A study was carried out in three home gardens in the Kandy district from May to December 2009 with the objectives of (a) identifying spatial distribution of terrestrial vertebrates in different vegetation strata, (b) their diurnal and seasonal variations, (c) plant-animal interactions, (d) nesting habits and (e) diet composition. A total of 93 terrestrial vertebrate species including seven amphibians, 23 mammals, 43 birds, and 20 reptiles were recorded. These comprised 14 endemic species, 71 native, four introduced mammals and two migrant birds. Terrestrial vertebrate assemblages were similar in Home garden 1 and 3. According to the fully-nested ANOVA, statistically significant differences were found in the composition of terrestrial vertebrates and the home gardens (P=0.005<0.05), and their vegetation strata (P=0.005<0.05). However, no statistically significant differences were observed between richness of terrestrial vertebrates and the monsoonal periods (P=0.966>0.05), as well as the time of the day (P=0.775>0.05). A positive relationship was obtained between canopy cover and number of bird nests in all home gardens (rs = +1, α = 0.05).Commensalism was the most frequently recorded relationship in all three home gardens. Overall, the diversity of animals and their interactions were different in the three Kandyan Home Gardens studied. Preventing the degradation of home gardens can be considered as a means of conserving biodiversity. There is scope to develop the Kandyan Home Garden system as an important strategy to conserve biodiversity outside the natural and protected area systems

    A Closed-Form Solution of the Multi-Period Portfolio Choice Problem for a Quadratic Utility Function

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    In the present paper, we derive a closed-form solution of the multi-period portfolio choice problem for a quadratic utility function with and without a riskless asset. All results are derived under weak conditions on the asset returns. No assumption on the correlation structure between different time points is needed and no assumption on the distribution is imposed. All expressions are presented in terms of the conditional mean vectors and the conditional covariance matrices. If the multivariate process of the asset returns is independent it is shown that in the case without a riskless asset the solution is presented as a sequence of optimal portfolio weights obtained by solving the single-period Markowitz optimization problem. The process dynamics are included only in the shape parameter of the utility function. If a riskless asset is present then the multi-period optimal portfolio weights are proportional to the single-period solutions multiplied by time-varying constants which are depending on the process dynamics. Remarkably, in the case of a portfolio selection with the tangency portfolio the multi-period solution coincides with the sequence of the simple-period solutions. Finally, we compare the suggested strategies with existing multi-period portfolio allocation methods for real data.Comment: 38 pages, 9 figures, 3 tables, changes: VAR(1)-CCC-GARCH(1,1) process dynamics and the analysis of increasing horizon are included in the simulation study, under revision in Annals of Operations Researc

    Bird communities and feeding guilds in Monaragala, an isolated hill in the eastern intermediate zone of Sri Lanka

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    The bird communities and foraging guilds were studied in the entire forest of Monaragala hill, by recording species and their abundances, in 33 plots (each 100x20 m), in four transects laid along its altitudinal gradient. Bird calls and sightings were noted for 30 minutes between 7.00-9.30 am, twice each month from 2004-2008.The communities were determined, by cluster and ordination analyses of data in all plots. For each community, relative abundance (RA) and frequency (RF) were calculated. Species were assigned to bird guilds based on their habitats, main food types and feeding strategies, from published informationWithin and outside the plots sampled, 112 bird species (23% of Sri Lanka‟s avifauna, including eight endemics) in 84 genera, 44 families and 13 orders, were recorded. Three communities were identified: i. a low/mid-elevation disturbed forest community (LDFC), inhabited by 40 species (including seven endemics). The Crimson-Fronted Barbet, Black Crested Bulbul and Tickell‟s Blue Flycatcher co-dominated it. ii. a ridge/upper-elevation undisturbed forest community (RUFC) of 45 species that included eight endemics, nine restricted species, the wet zone Sri Lanka Yellow Fronted Barbet and Sri Lanka Wood Pigeon. The Black Bulbul and Sri Lanka Yellow Fronted Barbet were its dominants. Thirty three species were common to both forest communities. iii. a grassland community, with only 10 non-endemic species, dominated by the Crested Tree Swift and Indian Swiftlet. Three grassland species were also seen in the forest communities.In each forest community ten bird guilds were present. The arboreal frugivore and gleaning insectivore guilds ranked highest in them, followed by the hawking/hovering insectivore guild in the LDFC, and the omnivore gleaning guild in the RUFC. The grassland community had only three guilds. Based on RA the sweeping insectivore guild and on RF the aerial carnivore and the sweeping insectivore guilds were co-dominant. The arboreal granivore guild was restricted to the grasslandThe study revealed that this intermediate zone, 43 km2 isolated hill (1,100 m amsl) harbors a rich avifauna, including some typical wet zone species, and rich populations of the rare Sri Lanka Spur fowl and the Sri Lanka Wood pigeon, justifying its high conservation value

    Dry Markets and Superreplication Bounds of American Derivatives

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    This paper studies the impact of dry markets for underlying assets on the pricing of American derivatives, using a discrete time framework. Dry markets are characterized by the possibility of non-existence of trading at certain dates. Such non-existence may be deterministic or probabilistic. Using superreplicating strategies, we derive expectation representations for the range of arbitrage-free values of the dervatives. In the probabilistic case, if we consider an enlarged filtration induced by the price process and the market existence process, ordinary stopping times are required. If not, randomized stopping times are required. Several comparisons of the ranges obtained with the two market restrictions are performed. Finally, we conclude that arbitrage arguments are not enough to define the optimal exercise policy.N/

    The ocean sampling day consortium

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    Ocean Sampling Day was initiated by the EU-funded Micro B3 (Marine Microbial Biodiversity, Bioinformatics, Biotechnology) project to obtain a snapshot of the marine microbial biodiversity and function of the world’s oceans. It is a simultaneous global mega-sequencing campaign aiming to generate the largest standardized microbial data set in a single day. This will be achievable only through the coordinated efforts of an Ocean Sampling Day Consortium, supportive partnerships and networks between sites. This commentary outlines the establishment, function and aims of the Consortium and describes our vision for a sustainable study of marine microbial communities and their embedded functional traits

    A comparison of methods to assess the antimicrobial activity of nanoparticle combinations on bacterial cells

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    Copyright: © 2018 Bankier et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.BACKGROUND: Bacterial cell quantification after exposure to antimicrobial compounds varies widely throughout industry and healthcare. Numerous methods are employed to quantify these antimicrobial effects. With increasing demand for new preventative methods for disease control, we aimed to compare and assess common analytical methods used to determine antimicrobial effects of novel nanoparticle combinations on two different pathogens. METHODS: Plate counts of total viable cells, flow cytometry (LIVE/DEAD BacLight viability assay) and qPCR (viability qPCR) were used to assess the antimicrobial activity of engineered nanoparticle combinations (NPCs) on Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) bacteria at different concentrations (0.05, 0.10 and 0.25 w/v%). Results were analysed using linear models to assess the effectiveness of different treatments. RESULTS: Strong antimicrobial effects of the three NPCs (AMNP0-2) on both pathogens could be quantified using the plate count method and flow cytometry. The plate count method showed a high log reduction (>8-log) for bacteria exposed to high NPC concentrations. We found similar antimicrobial results using the flow cytometry live/dead assay. Viability qPCR analysis of antimicrobial activity could not be quantified due to interference of NPCs with qPCR amplification. CONCLUSION: Flow cytometry was determined to be the best method to measure antimicrobial activity of the novel NPCs due to high-throughput, rapid and quantifiable results.Peer reviewe
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