P. Fernando, H. Janaka, M. K. C. R. De Silva, J. Pastorini
The Yala National Park is the premier protected area in Sri Lanka. Overcrowding has been an issue in Yala for over a decade. Information sharing by mobile communication was thought to result in safari jeeps flocking to favoured sightings, causing overcrowding and reckless driving. We assessed visitor satisfaction and the impact of switching off mobile communication towers providing park coverage, by conducting a questionnaire survey, checking signal strength and assessing vehicle speed. We found that visitor satisfaction was related to sightings of the ‘big three’, elephants, leopards and sloth bears, but not to overcrowding at sightings. Reckless driving impacted visitor satisfaction both negatively and positively. High speed driving was mostly due to trying to exit the park before the park-closure time. Switching off mobile communication towers reduced signal strength and accessibility but did not eliminate it. Reduced mobile coverage lessened overcrowding at sightings but also decreased sightings, resulting in an overall reduction of visitor satisfaction. We conclude that reducing or eliminating mobile communication is not a viable solution to overcrowding.
{"title":"Is restricting mobile communication a solution to overcrowding? A test from Yala National Park, Sri Lanka","authors":"P. Fernando, H. Janaka, M. K. C. R. De Silva, J. Pastorini","doi":"10.4038/cjs.v53i2.8289","DOIUrl":"https://doi.org/10.4038/cjs.v53i2.8289","url":null,"abstract":"The Yala National Park is the premier protected area in Sri Lanka. Overcrowding has been an issue in Yala for over a decade. Information sharing by mobile communication was thought to result in safari jeeps flocking to favoured sightings, causing overcrowding and reckless driving. We assessed visitor satisfaction and the impact of switching off mobile communication towers providing park coverage, by conducting a questionnaire survey, checking signal strength and assessing vehicle speed. We found that visitor satisfaction was related to sightings of the ‘big three’, elephants, leopards and sloth bears, but not to overcrowding at sightings. Reckless driving impacted visitor satisfaction both negatively and positively. High speed driving was mostly due to trying to exit the park before the park-closure time. Switching off mobile communication towers reduced signal strength and accessibility but did not eliminate it. Reduced mobile coverage lessened overcrowding at sightings but also decreased sightings, resulting in an overall reduction of visitor satisfaction. We conclude that reducing or eliminating mobile communication is not a viable solution to overcrowding.","PeriodicalId":9894,"journal":{"name":"Ceylon Journal of Science","volume":"105 22","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140987132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. S. D. Wickramasinghe, A. Attanayake, T. Wijesiri, H. H. Peiris, L.K.B. Mudduwa, A. S. D. Wickramasinghe¹, A. P. Attanayake², T. W. Wijesiri³, H. H. Peiris⁴, L.K.B. Mudduwa³
In search of new fangled therapeutic agents against type 2 diabetes mellitus (T2DM), an appropriate preclinical disease model is important to ensure the success of subsequent clinical trials. There is an increasing trend in the use of high-fat diet (HFD) fed streptozotocin (STZ)-induced rodent models in investigating novel therapeutic agents against T2DM. Though several studies have been conducted on the development of the aforementioned model they were mainly focused on biochemical characteristics. Only limited studies have focused on histopathological changes which is the gold standard in investigating the treatment-related changes of novel therapeutic agents. Therefore, the present study aimed at assessing the histopathological changes of the pancreas and liver, the two main organs involved in glucose homeostasis, in a newly developed HFD-fed STZ-induced Wistar rat model. For this study, Wistar rats were induced with T2DM by intraperitoneal injection of STZ (30, 40, and 50 mg/kg) which was given after feeding the rats with an HFD consisting of 60% calories from fat for four weeks duration. Diabetic rats were sacrificed after maintaining for further four weeks. The liver and pancreas were excised and hematoxylin and eosin-stained sections were observed using a light microscope. The major histopathological changes in the pancreas of HFD-fed STZ-induced diabetic rats were loss of pancreatic islets, pancreatic islet hypertrophy, and mild fatty change in the exocrine pancreas. In contrast, the liver did not show any degree of fatty change, but the majority showed prominent hydropic degeneration in the hepatocytes. In conclusion, prominent alterations were well noted in the pancreatic and liver tissues of the Wistar rats fed with HFD, followed by STZ (50 mg/kg), and the established model could be useful in investigating and elucidating antidiabetic mechanisms of novel pharmaceutical agents.
{"title":"Pancreatic and hepatic histopathology of high-fat diet fed streptozotocin-induced Wistar rat model of type 2 diabetes mellitus","authors":"A. S. D. Wickramasinghe, A. Attanayake, T. Wijesiri, H. H. Peiris, L.K.B. Mudduwa, A. S. D. Wickramasinghe¹, A. P. Attanayake², T. W. Wijesiri³, H. H. Peiris⁴, L.K.B. Mudduwa³","doi":"10.4038/cjs.v53i2.8274","DOIUrl":"https://doi.org/10.4038/cjs.v53i2.8274","url":null,"abstract":"In search of new fangled therapeutic agents against type 2 diabetes mellitus (T2DM), an appropriate preclinical disease model is important to ensure the success of subsequent clinical trials. There is an increasing trend in the use of high-fat diet (HFD) fed streptozotocin (STZ)-induced rodent models in investigating novel therapeutic agents against T2DM. Though several studies have been conducted on the development of the aforementioned model they were mainly focused on biochemical characteristics. Only limited studies have focused on histopathological changes which is the gold standard in investigating the treatment-related changes of novel therapeutic agents. Therefore, the present study aimed at assessing the histopathological changes of the pancreas and liver, the two main organs involved in glucose homeostasis, in a newly developed HFD-fed STZ-induced Wistar rat model. For this study, Wistar rats were induced with T2DM by intraperitoneal injection of STZ (30, 40, and 50 mg/kg) which was given after feeding the rats with an HFD consisting of 60% calories from fat for four weeks duration. Diabetic rats were sacrificed after maintaining for further four weeks. The liver and pancreas were excised and hematoxylin and eosin-stained sections were observed using a light microscope. The major histopathological changes in the pancreas of HFD-fed STZ-induced diabetic rats were loss of pancreatic islets, pancreatic islet hypertrophy, and mild fatty change in the exocrine pancreas. In contrast, the liver did not show any degree of fatty change, but the majority showed prominent hydropic degeneration in the hepatocytes. In conclusion, prominent alterations were well noted in the pancreatic and liver tissues of the Wistar rats fed with HFD, followed by STZ (50 mg/kg), and the established model could be useful in investigating and elucidating antidiabetic mechanisms of novel pharmaceutical agents.","PeriodicalId":9894,"journal":{"name":"Ceylon Journal of Science","volume":"115 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141003488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pteridophytes and lycophytes from Osomba Hills, a biodiversity hotspot in Nigeria, were collected using a transect method. Floristic sampling was done in six 100 m transects and elevation range of 170 m – 405 m above sea level where each transect consisted of five 10 m × 10 m quadrats spaced 10 m apart. Fieldwork was performed during the dry (February) and wet seasons (July) in 2022. F ifty species from 22 genera in the nine families Adiantaceae, Aspleniaceae, Cyatheaceae, Dennstaedtiaceae, Hymenophylaceae, Polypodiaceae, Pteridaceae, Schizaeaceae and Selaginellaceae were recorded. The lycophytes were represented by only one family, the Selaginellaceae, while the remaining eight families are pteridophytes. The family with the highest number of species was Polypodiaceae (21), while Cyatheaceae and Schizaeaceae recorded only 1 species each. Nine species were collected only in the dry season while 20 species were collected during the wet season. The remaining 21 species were identified in both dry and wet seasons. T he tree fern Alsophila camerooniana (Hook.) R. M. Tryon and the three species of Hymenophyllaceae were limited in range of occurrence. The diversity of these ferns was significant (P<0.05) within Osomba Hill. This variance was typified along latitudinal and temporal scales. The conservation status of 47 species were categorized as ‘Not Evaluated’. A comprehensive evaluation of the conservation status of these plants is recommended to enable the implementation of an appropriate conservation strategy by the management of the park.
{"title":"Pteridophytes and lycophytes from Osomba Hills, Cross River National Park, Nigeria","authors":"M. E. Bassey, E. Anwana, O. T. Umoh, E. Mbong","doi":"10.4038/cjs.v53i2.8188","DOIUrl":"https://doi.org/10.4038/cjs.v53i2.8188","url":null,"abstract":"Pteridophytes and lycophytes from Osomba Hills, a biodiversity hotspot in Nigeria, were collected using a transect method. Floristic sampling was done in six 100 m transects and elevation range of 170 m – 405 m above sea level where each transect consisted of five 10 m × 10 m quadrats spaced 10 m apart. Fieldwork was performed during the dry (February) and wet seasons (July) in 2022. F ifty species from 22 genera in the nine families Adiantaceae, Aspleniaceae, Cyatheaceae, Dennstaedtiaceae, Hymenophylaceae, Polypodiaceae, Pteridaceae, Schizaeaceae and Selaginellaceae were recorded. The lycophytes were represented by only one family, the Selaginellaceae, while the remaining eight families are pteridophytes. The family with the highest number of species was Polypodiaceae (21), while Cyatheaceae and Schizaeaceae recorded only 1 species each. Nine species were collected only in the dry season while 20 species were collected during the wet season. The remaining 21 species were identified in both dry and wet seasons. T he tree fern Alsophila camerooniana (Hook.) R. M. Tryon and the three species of Hymenophyllaceae were limited in range of occurrence. The diversity of these ferns was significant (P<0.05) within Osomba Hill. This variance was typified along latitudinal and temporal scales. The conservation status of 47 species were categorized as ‘Not Evaluated’. A comprehensive evaluation of the conservation status of these plants is recommended to enable the implementation of an appropriate conservation strategy by the management of the park.","PeriodicalId":9894,"journal":{"name":"Ceylon Journal of Science","volume":"87 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141022066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. A. D. S. P. Caldera, S. V. A. Almeida, G. S. Wijesiri
In Topological graph theory, the maximum genus of graphs has been a fascinating subject. For a simple connected graph G, the maximum genus γM(G) is the largest genus of an orientable surface on which G has a 2-cell embedding. γM(G) has the upper bound, γM(G)≤[β/2], where β(G) denotes the Betti number and G is said to be upper embeddable if the equality holds. In this study, the maximum genus of GP(n, k) is established as γM(GP(n,k))=[(n+1)/2] for k = 1 and k = 2 by proving the upper embeddability of generalized Petersen graph, GP(n, k) for the cases k = 1 and k = 2. The proof is done by obtaining spanning trees T and examining the components in the edge complements GP(n, k)T for the cases k = 1 and k = 2 of GP(n, k).
在拓扑图理论中，图的最大属是一个引人入胜的课题。对于简单连通图 G，最大图属 γM(G)是 G 在其上有 2 单元嵌入的可定向曲面的最大图属。γM(G)有上界，γM(G)≤[β/2]，其中β(G)表示贝蒂数，如果相等成立，则称 G 为上可嵌入。在本研究中，通过证明广义彼得森图 GP(n, k) 在 k = 1 和 k = 2 两种情况下的上可嵌入性，确定了在 k = 1 和 k = 2 时 GP(n, k) 的最大属数为 γM(GP(n,k))=[(n+1)/2]。证明的方法是获取生成树 T，并检查 GP(n, k) 的 k = 1 和 k = 2 两种情况下的边补 GP(n, k)T 中的成分。
{"title":"The maximum genus of the generalized Petersen Graph, GP (n, k) for the cases k = 1, 2","authors":"P. A. D. S. P. Caldera, S. V. A. Almeida, G. S. Wijesiri","doi":"10.4038/cjs.v53i2.8146","DOIUrl":"https://doi.org/10.4038/cjs.v53i2.8146","url":null,"abstract":"In Topological graph theory, the maximum genus of graphs has been a fascinating subject. For a simple connected graph G, the maximum genus γM(G) is the largest genus of an orientable surface on which G has a 2-cell embedding. γM(G) has the upper bound, γM(G)≤[β/2], where β(G) denotes the Betti number and G is said to be upper embeddable if the equality holds. In this study, the maximum genus of GP(n, k) is established as γM(GP(n,k))=[(n+1)/2] for k = 1 and k = 2 by proving the upper embeddability of generalized Petersen graph, GP(n, k) for the cases k = 1 and k = 2. The proof is done by obtaining spanning trees T and examining the components in the edge complements GP(n, k)T for the cases k = 1 and k = 2 of GP(n, k).","PeriodicalId":9894,"journal":{"name":"Ceylon Journal of Science","volume":"15 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141022737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. A. S. R. Ranasinghe, K. A. C. Rathnathilaka, P. Karunarathna, P. Samarasekara
Metal oxides and carbon are the prime candidates of gas sensor devices. For the inaugural instance, carbonaceous particulate matter was meticulously derived from the branches of Acacia auriculiformis tree indigenous to Sri Lanka to detect vapor and gas. It is worth noting that biomass derived carbon had hitherto remain unexplored in the realm of vapor and gas detection. Carbon films were fabricated via the doctor blade method. The resistivity characteristic of these carbon samples exhibited discernible variations upon exposure to methanol, ethanol, acetone vapors, and ammonia gas. Notably, the gas-sensing properties of sample derived from the central core and the outer shell of Acacia auriculiformis tree branches were independently assessed in these vapors and gas at ambient temperature. Various analytical techniques, including X-ray diffraction (XRD), UVvisible absorption spectroscopy, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM), were judiciously employed to scrutinize the structural attribute, optical band gap, chemical composition and surface morphology of the aforementioned carbon film samples, respectively. XRD analyses unequivocally confirmed the successful formation of carbonaceous films. FTIR spectra conspicuously delineated the presence of oxygen within the carbon films. Importantly, the optical band gap of our carbon films manifested within the range characteristic of organic carbon. Furthermore, the resistance of the carbon films demonstrated a significant reduction upon adsorption of each vapor. It is noteworthy that while gas sensitivities and response times were superior for carbon derived from the central core of the Acacia tree branches, the recovery times were notably expedited for carbon synthesized from the outer shell of these branches. The zenith of gas sensitivity, an impressive 187%, was recorded in response to 1000 ppm of methanol vapor, when employing carbon sourced from the central core of the acacia tree branches.
金属氧化物和碳是气体传感器装置的主要候选材料。首次使用的碳质颗粒物是从斯里兰卡本土的金合欢树枝条中精心提取的，用于检测蒸汽和气体。值得注意的是，从生物质中提取的碳迄今为止在蒸汽和气体检测领域仍未得到开发。碳膜是通过刮刀法制造的。在暴露于甲醇、乙醇、丙酮蒸汽和氨气时，这些碳样品的电阻率特征会出现明显的变化。值得注意的是，在这些蒸汽和气体的环境温度下，对从金合欢树枝的中心核和外壳中提取的样品的气体感应特性进行了独立评估。研究人员采用了多种分析技术，包括 X 射线衍射（XRD）、紫外可见吸收光谱、傅立叶变换红外光谱（FTIR）和扫描电子显微镜（SEM），分别对上述碳膜样品的结构属性、光带隙、化学成分和表面形态进行了仔细研究。XRD 分析明确证实了碳质薄膜的成功形成。傅立叶变换红外光谱明显显示了碳膜中氧气的存在。重要的是，碳膜的光带隙在有机碳的特征范围内。此外，碳膜的电阻在吸附每种蒸气后都会显著降低。值得注意的是，虽然从金合欢树树枝的中心核心提取的碳的气体灵敏度和响应时间更优，但从这些树枝的外壳合成的碳的恢复时间明显更快。在对 1000 ppm 的甲醇蒸气做出反应时，气体灵敏度达到了顶峰，达到了令人印象深刻的 187%。
{"title":"Carbon gas sensors synthesized using acacia auriculiformis tree branches to detect methanol, ethanol, acetone vapors and ammonia gas","authors":"R. A. S. R. Ranasinghe, K. A. C. Rathnathilaka, P. Karunarathna, P. Samarasekara","doi":"10.4038/cjs.v53i2.8412","DOIUrl":"https://doi.org/10.4038/cjs.v53i2.8412","url":null,"abstract":"Metal oxides and carbon are the prime candidates of gas sensor devices. For the inaugural instance, carbonaceous particulate matter was meticulously derived from the branches of Acacia auriculiformis tree indigenous to Sri Lanka to detect vapor and gas. It is worth noting that biomass derived carbon had hitherto remain unexplored in the realm of vapor and gas detection. Carbon films were fabricated via the doctor blade method. The resistivity characteristic of these carbon samples exhibited discernible variations upon exposure to methanol, ethanol, acetone vapors, and ammonia gas. Notably, the gas-sensing properties of sample derived from the central core and the outer shell of Acacia auriculiformis tree branches were independently assessed in these vapors and gas at ambient temperature. Various analytical techniques, including X-ray diffraction (XRD), UVvisible absorption spectroscopy, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM), were judiciously employed to scrutinize the structural attribute, optical band gap, chemical composition and surface morphology of the aforementioned carbon film samples, respectively. XRD analyses unequivocally confirmed the successful formation of carbonaceous films. FTIR spectra conspicuously delineated the presence of oxygen within the carbon films. Importantly, the optical band gap of our carbon films manifested within the range characteristic of organic carbon. Furthermore, the resistance of the carbon films demonstrated a significant reduction upon adsorption of each vapor. It is noteworthy that while gas sensitivities and response times were superior for carbon derived from the central core of the Acacia tree branches, the recovery times were notably expedited for carbon synthesized from the outer shell of these branches. The zenith of gas sensitivity, an impressive 187%, was recorded in response to 1000 ppm of methanol vapor, when employing carbon sourced from the central core of the acacia tree branches.","PeriodicalId":9894,"journal":{"name":"Ceylon Journal of Science","volume":"27 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141021526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. P. Kariyawasam, G. M. Somaratne, D. Roy, D. D. Silva, W. A. O. W. Weththasinghe, D. W. N. Sandanika
Isotonic drinks maintain a balance of salt and sugar concentrations similar to that of the human body, aiding in the rapid replacement of lost fluids during dehydration. Although the availability of isotonic beverages in the Sri Lankan market is limited, this segment is experiencing rapid growth on the global stage, with numerous brands marketing their products. Moreover, it is especially advantageous to create isotonic beverages tailored to tropical country consumers, given their ability to effectively replenish lost fluids due to dehydration. This study seeks to develop economically viable and commercially feasible formulations of isotonic drinks that cater to the preferences of Sri Lankan consumers, utilizing a combination of synthetic and natural ingredients. In the realm of natural isotonic beverages, coconut water and bee honey serve as excellent sources of electrolytes and sugar, respectively. Following osmolality and sensory evaluations, the chosen samples underwent further analysis to determine their mineral content and physicochemical characteristics. These developed formulations fall within the prescribed ranges for osmolality (270-330 mOsm/kg) and sodium content (460-1150 mg. L-1), aligning with international standards for isotonic beverages. In conclusion, the devised formulas successfully adhere to international specifications for isotonic beverages. The abundant potential of coconut water and bee honey in Sri Lanka with wide availability as valuable sources of minerals and energy for crafting isotonic drinks is evident.
{"title":"Development of Two Types of Isotonic Beverages with Functional Attributes Using Natural and Synthetic Ingredients","authors":"K. P. Kariyawasam, G. M. Somaratne, D. Roy, D. D. Silva, W. A. O. W. Weththasinghe, D. W. N. Sandanika","doi":"10.4038/cjs.v53i2.8276","DOIUrl":"https://doi.org/10.4038/cjs.v53i2.8276","url":null,"abstract":"Isotonic drinks maintain a balance of salt and sugar concentrations similar to that of the human body, aiding in the rapid replacement of lost fluids during dehydration. Although the availability of isotonic beverages in the Sri Lankan market is limited, this segment is experiencing rapid growth on the global stage, with numerous brands marketing their products. Moreover, it is especially advantageous to create isotonic beverages tailored to tropical country consumers, given their ability to effectively replenish lost fluids due to dehydration. This study seeks to develop economically viable and commercially feasible formulations of isotonic drinks that cater to the preferences of Sri Lankan consumers, utilizing a combination of synthetic and natural ingredients. In the realm of natural isotonic beverages, coconut water and bee honey serve as excellent sources of electrolytes and sugar, respectively. Following osmolality and sensory evaluations, the chosen samples underwent further analysis to determine their mineral content and physicochemical characteristics. These developed formulations fall within the prescribed ranges for osmolality (270-330 mOsm/kg) and sodium content (460-1150 mg. L-1), aligning with international standards for isotonic beverages. In conclusion, the devised formulas successfully adhere to international specifications for isotonic beverages. The abundant potential of coconut water and bee honey in Sri Lanka with wide availability as valuable sources of minerals and energy for crafting isotonic drinks is evident.","PeriodicalId":9894,"journal":{"name":"Ceylon Journal of Science","volume":"23 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140672268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. M. H. R. Dissanayaka, M. D. Pabasara, G. K. S. N. Gajanayake, W. Daundasekera, H. A. C. K. Ariyarathna
Blast disease caused by Magnaporthe sp. is one of the most destructive diseases in cereal crops. Disease infection was studied in farmer fields. Field data was recorded and further information was gathered by interviewing the farmers and agrarian extension officers. Blast infections were assessed in the fields using a standard evaluation system for rice (SES IRRI, 1996). Although symptoms were not observed in seedlings when mature rice fields were infected farmers experienced 100% yield loss. There were no or few leaf symptoms in blast infected mature rice fields yet neck infections were scored as 9 in SES. Unlike rice, leaf blast at seedling stage caused economic losses in finger millet. Mature finger millet fields were susceptible to neck and finger blast. Due to rapid disease development curative fungicide treatment was ineffective in controlling blast. Farmers reported sudden changes in the weather during infections whereby gloomy weather caused a spike in humidity and low temperatures that coincided with the infection. Host susceptibility window synchronized with conducive environments result in severe blast infections therefore, blast disease management needs a coordinated effort and system level interventions whereby control measures and use of resistant germplasm can be combined with climate-based disease predictions to increase the efficiency of disease control.
{"title":"A case report on Blast disease in Rice and Finger millet in Sri Lanka","authors":"D. M. H. R. Dissanayaka, M. D. Pabasara, G. K. S. N. Gajanayake, W. Daundasekera, H. A. C. K. Ariyarathna","doi":"10.4038/cjs.v53i2.8399","DOIUrl":"https://doi.org/10.4038/cjs.v53i2.8399","url":null,"abstract":"Blast disease caused by Magnaporthe sp. is one of the most destructive diseases in cereal crops. Disease infection was studied in farmer fields. Field data was recorded and further information was gathered by interviewing the farmers and agrarian extension officers. Blast infections were assessed in the fields using a standard evaluation system for rice (SES IRRI, 1996). Although symptoms were not observed in seedlings when mature rice fields were infected farmers experienced 100% yield loss. There were no or few leaf symptoms in blast infected mature rice fields yet neck infections were scored as 9 in SES. Unlike rice, leaf blast at seedling stage caused economic losses in finger millet. Mature finger millet fields were susceptible to neck and finger blast. Due to rapid disease development curative fungicide treatment was ineffective in controlling blast. Farmers reported sudden changes in the weather during infections whereby gloomy weather caused a spike in humidity and low temperatures that coincided with the infection. Host susceptibility window synchronized with conducive environments result in severe blast infections therefore, blast disease management needs a coordinated effort and system level interventions whereby control measures and use of resistant germplasm can be combined with climate-based disease predictions to increase the efficiency of disease control.","PeriodicalId":9894,"journal":{"name":"Ceylon Journal of Science","volume":"21 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140666540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mahesh Senarathna, R. Jayaratne, S. Abeysundara, R. Weerasooriya, Kosala Welikannage, Lidia Morawska, G. Bowatte
Air pollution is the leading environmental hazard that has devastating health effects on human health. Identification of trends and patterns of air pollution is crucial in a specific geographic area to inform and implement effective control and mitigation measurements. Standard air pollution monitoring networks are costly for most low-and middle-income countries. The aim of this study was to investigate the variations in the mean concentrations of air pollutants that occur at various times of the day, days of the week, months of the year, and seasons during the period of January 2019 to December 2019 in Kandy, Sri Lanka using low-cost sensors. A regression analysis with dummy variables was used to model the relationship between the concentrations of air pollutants and categorical independent variables, the time of day and day of the week. Considering temporal variations, the study found that pollution is highest in the early morning and evening, and lowest in the afternoon. The worst days for the air quality were Wednesdays and Thursdays, while Sundays had the lowest PM2.5 pollution. The analysis of air quality variations by month showed that December had the lowest air pollution of the examined months. The variation in PM2.5 was greatly influenced by wind speed, wind direction, and rainfall patterns. The study emphasized the importance of long-term consistently management and monitoring of air pollution levels.
{"title":"PM2.5 air pollution trends and patterns in Kandy, Sri Lanka","authors":"Mahesh Senarathna, R. Jayaratne, S. Abeysundara, R. Weerasooriya, Kosala Welikannage, Lidia Morawska, G. Bowatte","doi":"10.4038/cjs.v53i2.8403","DOIUrl":"https://doi.org/10.4038/cjs.v53i2.8403","url":null,"abstract":"Air pollution is the leading environmental hazard that has devastating health effects on human health. Identification of trends and patterns of air pollution is crucial in a specific geographic area to inform and implement effective control and mitigation measurements. Standard air pollution monitoring networks are costly for most low-and middle-income countries. The aim of this study was to investigate the variations in the mean concentrations of air pollutants that occur at various times of the day, days of the week, months of the year, and seasons during the period of January 2019 to December 2019 in Kandy, Sri Lanka using low-cost sensors. A regression analysis with dummy variables was used to model the relationship between the concentrations of air pollutants and categorical independent variables, the time of day and day of the week. Considering temporal variations, the study found that pollution is highest in the early morning and evening, and lowest in the afternoon. The worst days for the air quality were Wednesdays and Thursdays, while Sundays had the lowest PM2.5 pollution. The analysis of air quality variations by month showed that December had the lowest air pollution of the examined months. The variation in PM2.5 was greatly influenced by wind speed, wind direction, and rainfall patterns. The study emphasized the importance of long-term consistently management and monitoring of air pollution levels.","PeriodicalId":9894,"journal":{"name":"Ceylon Journal of Science","volume":"40 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140667120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. M. Manel, K. Herath, T. Weeraratne, S. P. Karunaratne
Vector resistance to insecticides is a significant challenge in the control of mosquito-borne diseases such as dengue. Analysis of the growth rate and survivorship of the immature stages of larvae has been important in formulating effective vector control strategies. The present study aimed to assess insecticide resistance in both larvae and adults of Aedes aegypti and Ae. albopictus, and the life tables of their immature stages.Mosquito eggs collected from Kurunegala and Colombo districts of Sri Lanka from January to March 2023 were reared under laboratory conditions. Larval bioassays were carried out with temephos (0.0125 ppm, 0.0625ppm and 0.125ppm) and, the adult bioassays were with pyrethroids (0.03% deltamethrin, 0.05% and 0.08% lambdacyhalothrin, 0.04% permethrin) and malathion (1%and 5%). Biochemical assays were used to evaluate the activity of insecticide-detoxifying enzymes and the insensitivity of the organophosphate target site acetylcholinesterase. Survivorship of immature stages under laboratory conditions and semi-field conditions i.e., bamboo stumps, tyres and clay pots, were studied using Kaplan-Meier survival analysis.Larvae and adults of both species from Kurunegala were susceptible to all the insecticides tested, whereas Colombo populations were resistant. Acetylcholinesterases were largely sensitive in all vector populations. Higher activities of esterases, glutathione s-transferases and monooxygenases were found in Colombo populations. Results indicated that Ae. aegypti larvae were more resistant to insecticides than Ae. albopictus larvae. Also, the mechanisms of insecticide resistance were well developed in adults than in larvae.Aedes aegypti larval development time (5 days) was significantly shorter than that of Ae. albopictus (9 days) under laboratory conditions. Survival probabilities of them were 76-80%. Egg hatching to adult emergence period was 8 days for Ae. aegypti and 13 days for Ae. albopictus. This period, under semifield conditions were; bamboo stumps 7-7.2 days, tyres 10-11.3 days, and clay pots 13.8-14 days with survival rates varied from 28.8 to 63% for both species. This study highlights stage specific response of dengue vectors to insecticides and survivorship of their immature stages in different habitats. This knowledge can be effectively used in future dengue vector control programmes.
{"title":"Stage-specific insecticide susceptibility and life-table analysis of the dengue vector mosquitoes Aedes aegypti and Ae. albopictus","authors":"J. M. Manel, K. Herath, T. Weeraratne, S. P. Karunaratne","doi":"10.4038/cjs.v53i2.8301","DOIUrl":"https://doi.org/10.4038/cjs.v53i2.8301","url":null,"abstract":"Vector resistance to insecticides is a significant challenge in the control of mosquito-borne diseases such as dengue. Analysis of the growth rate and survivorship of the immature stages of larvae has been important in formulating effective vector control strategies. The present study aimed to assess insecticide resistance in both larvae and adults of Aedes aegypti and Ae. albopictus, and the life tables of their immature stages.Mosquito eggs collected from Kurunegala and Colombo districts of Sri Lanka from January to March 2023 were reared under laboratory conditions. Larval bioassays were carried out with temephos (0.0125 ppm, 0.0625ppm and 0.125ppm) and, the adult bioassays were with pyrethroids (0.03% deltamethrin, 0.05% and 0.08% lambdacyhalothrin, 0.04% permethrin) and malathion (1%and 5%). Biochemical assays were used to evaluate the activity of insecticide-detoxifying enzymes and the insensitivity of the organophosphate target site acetylcholinesterase. Survivorship of immature stages under laboratory conditions and semi-field conditions i.e., bamboo stumps, tyres and clay pots, were studied using Kaplan-Meier survival analysis.Larvae and adults of both species from Kurunegala were susceptible to all the insecticides tested, whereas Colombo populations were resistant. Acetylcholinesterases were largely sensitive in all vector populations. Higher activities of esterases, glutathione s-transferases and monooxygenases were found in Colombo populations. Results indicated that Ae. aegypti larvae were more resistant to insecticides than Ae. albopictus larvae. Also, the mechanisms of insecticide resistance were well developed in adults than in larvae.Aedes aegypti larval development time (5 days) was significantly shorter than that of Ae. albopictus (9 days) under laboratory conditions. Survival probabilities of them were 76-80%. Egg hatching to adult emergence period was 8 days for Ae. aegypti and 13 days for Ae. albopictus. This period, under semifield conditions were; bamboo stumps 7-7.2 days, tyres 10-11.3 days, and clay pots 13.8-14 days with survival rates varied from 28.8 to 63% for both species. This study highlights stage specific response of dengue vectors to insecticides and survivorship of their immature stages in different habitats. This knowledge can be effectively used in future dengue vector control programmes.","PeriodicalId":9894,"journal":{"name":"Ceylon Journal of Science","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140723441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Here, we have improved a model to describe the flow variables, velocity, mass and heat transfer in the boundary layer region of modified second-grade fluid flow over a linearly stretched sheet in a porous media. The modified model is used to study the qualitative impact of buoyancy parameter, second-grade fluid parameter, magnetic parameters, porous parameter, power-law index, and chemical reaction parameter on the flow profiles, radial and axial velocities, temperature, and concentration. Starting with the steady-state governing equations of mass, momentum, heat, and concentration of the fluid flow, we obtained the boundary layer approximations of the flow near the linearly stretched sheet with the no-slip boundary condition. Similarity transformation has been used to convert the partial differential equations system into a nonlinear ordinary differential equations system. The radial velocities, temperature, and concentration profiles have been solved numerically, and the qualitative influence of the flow parameters on the flow variables has been simulated and graphically presented for comparison. We have observed that radial and axial velocities were increasing for the shear-thinning and shearthickening fluids with solutal Grashof number, thermal Grashof number and second-grade fluid parameters. In contrast, the porous and chemical reaction parameters slow down both fluids’ radial and axial velocities. The temperature and concentration increase with the porous and magnetic parameters. However, thermal and solutal Grashof and second-grade fluid parameters suppress temperature and concentration. In shear-thickening fluids, chemical reaction parameters enhance concentration but suppress in shear-thinning fluids.
{"title":"Mass and heat transfer in the boundary layer region of modified second-grade fluid flow over a linearly stretched sheet embedded in porous media","authors":"N. Karunathilake, L.M.N.Fernando","doi":"10.4038/cjs.v53i2.8260","DOIUrl":"https://doi.org/10.4038/cjs.v53i2.8260","url":null,"abstract":"Here, we have improved a model to describe the flow variables, velocity, mass and heat transfer in the boundary layer region of modified second-grade fluid flow over a linearly stretched sheet in a porous media. The modified model is used to study the qualitative impact of buoyancy parameter, second-grade fluid parameter, magnetic parameters, porous parameter, power-law index, and chemical reaction parameter on the flow profiles, radial and axial velocities, temperature, and concentration. Starting with the steady-state governing equations of mass, momentum, heat, and concentration of the fluid flow, we obtained the boundary layer approximations of the flow near the linearly stretched sheet with the no-slip boundary condition. Similarity transformation has been used to convert the partial differential equations system into a nonlinear ordinary differential equations system. The radial velocities, temperature, and concentration profiles have been solved numerically, and the qualitative influence of the flow parameters on the flow variables has been simulated and graphically presented for comparison. We have observed that radial and axial velocities were increasing for the shear-thinning and shearthickening fluids with solutal Grashof number, thermal Grashof number and second-grade fluid parameters. In contrast, the porous and chemical reaction parameters slow down both fluids’ radial and axial velocities. The temperature and concentration increase with the porous and magnetic parameters. However, thermal and solutal Grashof and second-grade fluid parameters suppress temperature and concentration. In shear-thickening fluids, chemical reaction parameters enhance concentration but suppress in shear-thinning fluids.","PeriodicalId":9894,"journal":{"name":"Ceylon Journal of Science","volume":"112 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140724509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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