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Journal Cover Journal of the National Science Foundation of Sri Lanka
  [SJR: 0.166]   [H-I: 8]   [2 followers]  Follow
    
  This is an Open Access Journal Open Access journal
   ISSN (Print) 1391-4588
   Published by Sri Lanka Journals Online Homepage  [48 journals]
  • Editorial

    • Abstract: JNSF December 2017 issue Published on 2017-12-27 00:00:00
       
  • Arbuscular mycorrhizal fungal dynamics following change of land use from
           mature forest to Eucalyptus plantation

    • Abstract: Change of arbuscular mycorrhizal fungi (AMF) dynamics following land use change was investigated. A study was carried out using four land use types viz., a mature forest (MF), a Eucalyptus plantation (EP: which was established after clearing mature forests in the area in 1980s) and two regenerating forests (Re: following clear-cut of Eucalyptus in 2005), where one is bordered by a Eucalyptus plantation (Re-EP) and the other bordered by a mature forest (Re-MF), located in the Intermediate Zone of Sri Lanka. Soil samples were collected from each land use type and the AMF spores were quantified and identified into morphotypes. Percentage AMF colonisation in fine roots was also quantified. Some basic soil parameters (pH, soil moisture, available P and total C) were also tested. A total of 24,698; 16,379; 15,791 and 15,165 spores were recovered from MF, EP, Re-EP and Re-MF, respectively. The number of morphotypes was 14, 13, 11 and 9 in Re-EP, EP, MF and Re-MF, respectively. The MF showed the highest diversity index (0.970), followed by EP, Re-EP and Re-MF. The MF showed a significantly higher average number of spores (2,058) compared to EP, Re-EP and Re-MF (1,365; 1,316 and 1,264, respectively). Out of 19 morphotypes, 5 (26 %) were observed in all land use types, while 4 (21 %) were observed exclusively in Re-EP. Percentage root colonisation was significantly higher in MF (≈70 %) than in other land use types (52 – 53 %). The MF showed a higher soil moisture and total organic matter content than the rest of the study sites, with no significant difference in available P. The results indicate that the change of land use has clearly altered the abundance and composition of the AMF population. Published on 2017-12-27 00:00:00
       
  • Microbial biofilms and mitigation of loss of agro-biodiversity in degraded
           soils

    • Abstract: Modern agriculture has been one of the causes for biodiversity degradation. Conservation of the remaining biodiversity is of utmost importance and novel approaches and concepts should be tested to achieve this end. As a recent development in microbiology, fungal surface-attached bacterial communities or fungal-bacterial biofilms (FBBs) are being studied for various biotechnological applications with consequences in ecosystem functioning and biodiversity. The present study was conducted to investigate the effect of the introduced FBBs on restoration of reduced biodiversity in the soil of a degraded tea land. The soil was treated with a developed biofilm, its monocultures, the nutrient solution used for culturing the microbes, and sterilised distilled water in a pot experiment. After three months, the soils were evaluated for plant and culturable microbial species richness, microfaunal count, nitrogenase activity, and selected soil parameters. It was observed that the biofilm application resulted in a significantly higher plant species richness than the respective monocultures (p < 0.05). Further, culturable bacterial and fungal species richnesses, soil nitrogenase activity, organic carbon, and available ammonium and nitrate increased significantly with the biofilm application, compared with the application of the nutrient solution and distilled water (p < 0.05). Results of the present study indicated that inoculation of the developed microbial biofilms influences microbial and plant diversity and soil quality parameters positively. These observations indicate that the microbial biofilms developed in this study may have the potential to be developed as a novel biotechnological tool to mitigate biodiversity loss in agroecosystems and perhaps in natural ecosystems. Published on 2017-12-27 00:00:00
       
  • A study of obstacle problems using homotopy perturbation method

    • Abstract: Numerical methods for solving differential equations  has become an important topic of this era. The importance of  boundary value problems in applied sciences shows the way  in which existence of exact solution is not always possible.  This study adopts the homotopy perturbation method (HPM)  to solve multiple-point boundary value problems arising  in obstacle, unilateral and contact problems. Convergent  approximate solutions are constructed such that the exact  boundary conditions are satisfied. Some examples have been  presented to elucidate the efficiency and implementation of the  method. We have compared the results using different number  of terms of HPM and found that increasing the number of terms  of approximate solution will increase the efficiency.   Published on 2017-12-27 00:00:00
       
  • Genetic variation, character association and evaluation of mungbean
           genotypes for agronomic and yield components

    • Abstract: Forty genotypes of mungbean were evaluated  to compare the genetic divergence and association among  agronomic and yield characteristics. Analysis of variance  indicated highly significant (p < 0.01) differences for all  the traits except for 1000 seed weight. The phenotypic and  genotypic coefficient of variation was the highest for grain yield  per plant, followed by pod length. High broad sense heritability  (> 60 %) along with high genetic advance was observed for  total yield per plant, pod length, number of seeds per pod and  plant height, indicating that these characteristics would be best  for phenotypic selection. A significant negative correlation  was observed between days to flowering and total yield per  plant. Positive correlations were observed between plant  height, pod length and 1000 seed weight with total yield per  plant. Multivariate analysis showed that the first three principal  components cumulatively accounted for 69.77 % of the total  variation. The present findings could be useful in selecting  superior genotypes in mungbean breeding programmes. Published on 2017-12-27 00:00:00
       
  • Fabrication and evaluation of an all solid redox capacitor with an iodine
           based gel polymer electrolyte

    • Abstract: Gel polymer electrolytes (GPEs) have demonstrated a greater potential to be used as electrolytes for various applications such as batteries, super capacitors, electrochromic devices and dye sensitised solar cells. They consist of a salt and a mixture of solvents trapped in a polymer matrix. In this study, optimisation and characterisation of a GPE consisting of polyvinylidene fluoride, ethylene carbonate, propylene carbonate and sodium iodide and its application in a redox capacitor with two polypyrrole electrodes was studied. GPE shows a conductivity of 9.69 × 10-3 Scm-1 at room temperature (28 °C) with good mechanical stability. The corresponding composition is 1.13 PVdF : 2.5 EC : 2.5 PC : 0.4 NaI (by weight). The variation of conductivity with temperature follows Arhenius behaviour suggesting that the conductivity mechanism takes place via hopping of ions. Conductivity is purely ionic in nature. Properties of the redox capacitors were studied by the cyclic voltammetry (CV) technique, electrochemical impedance spectroscopy (EIS) technique and galvanostatic charge-discharge (GCD) test. The CV results showed the dependency of specific capacitance on the scan rate. The EIS results showed that capacitive behaviour becomes dominant only at low frequency range. The resulting specific capacitance was 3.19 Fg-1. It was found that the redox capacitor exhibits an average discharge specific capacitance of 5.93 Fg-1 while having a specific energy density of 0.03 Whkg-1 and a specific power density of 0.42 Wkg-1. Published on 2017-12-27 00:00:00
       
  • Rhizobial inoculation of Trifolium repens L. in Sri Lanka

    • Abstract: The objective of this study was to develop an  environmental friendly, low cost technology for cultivation  of livestock forage legumes so as to minimise the use of  nitrogen fertiliser (N-fertiliser) that pollute the pristine  highland watersheds. Inoculants were prepared by screening  several rhizobial isolates obtained from farm cultivated clover  plants and selecting the most efficient strain. In field tests at  three separate sites, the average amount of biomass produced  by inoculated Trifolium plants was higher compared with the  plants fertilised with urea. Root nodulation and other plant  parameters were assessed on several randomly harvested plants  60 days after planting. The results indicate that root nodulation  and plant growth increased significantly in inoculated plants.  Average results obtained from nine crop cuts taken during a  period of 15 months showed that regeneration and biomass  production after crop cutting were better under inoculation  than under N-fertiliser application. It is inferred that rhizobial  inoculation has the potential to replace N-fertiliser applications  to Trifolium repens L. in the Sri Lankan highland farming  systems.   Published on 2017-12-27 00:00:00
       
  • Influence of fuzzy index parameter on FSVM classifier performance

    • Abstract: Support vector machine (SVM), a machine learning algorithm used extensively for pattern analysis and recognition, is found sensitive to outliers and noise. Fuzzy support vector machine (FSVM) has been used in many applications as a most prominent technique by researchers to overcome the sensitivity issue faced by SVM, and for its good generalisation performance. In this research, a method to justify the performance of FSVM classifier by showing the influence of fuzzy index m on membership function of the model has been proposed. In the first phase of the study, an algorithm to find the optimal fuzzy index using fuzzy C-means (FCM) and to avoid testing all fuzzy index values on the FSVM model has been proposed. The operational complexity of the model can be reduced by this process. In the second phase of this study a FSVM algorithm to incorporate new membership function is proposed. The model is tested on six different datasets and kernel functions and the kernel with the highest classification accuracy is identified as an efficient kernel for the applied dataset. The experimental results on the chosen fuzzy index have proven that the proposed alternate methodology enhances classifier accuracy compared to other research findings. Hence, the model could be applied to diverse fields of FSVM applications.  Published on 2017-12-27 00:00:00
       
  • The identity of the violet flowered water lily (Nymphaeaceae) and its
           hybrid origin in the wetland ecosystems of Sri Lanka

    • Abstract: The Sri Lankan violet water lily (Dam-manel) that is widely spread in natural water bodies of the country has been erroneously identified as Nymphaea nouchali (Nil-manel) in literature. Further the image of this flower, which has been erroneously used to depict the national flower of the country for nearly three decades, has not been taxonomically described and therefore does not have a botanical identity. Many scientific studies have been conducted on different aspects of the violet coloured water lily under either the erroneous identification or without a proper scientific name. The present study was conducted with the aim of clarifying its confused identity with N. nouchali, and also elucidating the parentage of the hybrid origin of Sri Lankan violet water lily using morphological and matK and psbA-trnH molecular sequence data. The morphometric analyses and the results of the BLAST search confirmed the identity of the native N. nouchali, and recognised the Sri Lankan violet water lily as a hybrid of N. micrantha and N. caerulea. Therefore, the plant is named and described as a new hybrid, Nymphaea × erangae Yakandawala, Guruge & Yakandawala. A taxonomic description is also provided for the newly described hybrid. Published on 2017-12-27 00:00:00
       
  • Breaking Speck cryptosystem using correlation power analysis attack

    • Abstract: This is an empirical study based on correlation power analysis for extracting the secret key from a Speck based embedded cryptosystem. Speck was recently introduced by the National Security Agency, USA as a lightweight softwarebased block cipher targetting embedded systems. The pervasive nature of embedded devices makes it crucial to perform this assessment. We empirically show that the secret key of a Speck cryptosystem can be extracted within an hour on a microcontroller based embedded system. The experiments were performed in three different microcontrollers with different bit widths and power settings. It is concluded that although Speck is new, it is vulnerable to power analysis attack.  Published on 2017-12-27 00:00:00
       
 
 
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