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Food Hygiene and Safety Practices amongst Food Vendors in the Western Area, Sierra Leone
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作者 Philip John Kanu Hamid Turay 《Food and Nutrition Sciences》 CAS 2024年第6期421-431,共11页
Food safety and hygiene practices require a multisectoral approach including food, water, sanitation, waste management, transport, education, trade, policies and programs that enable safe food preparation, storage and... Food safety and hygiene practices require a multisectoral approach including food, water, sanitation, waste management, transport, education, trade, policies and programs that enable safe food preparation, storage and service. Unsafe food can cause illness keeping people from achieving their full potential and death. This was a descriptive study that uses a mixed method approach to derive insights into the characteristics of food vendors related to demography, knowledge, practices, infrastructure, compliance and recommendation for a policymaking framework. Using the Lemeshows’ sample size formula, 473 vendors from formal (restaurants) and informal (cookri-baffa/table top) sites were interviewed and observed. We found from discussions that respondents had a good understanding on how to keep food safe. However, observed practices were poor 93% handled food with their bare hands, 83% did not cover their hair, and 76% did not wear an apron whilst handling, preparing or serving food, 61% did not keep their finger nails clean or short and 57% did not wash their hand before preparing or serving food. Over half (51%) had access to a toilet but 32% reported their use required payment and emphasized their poor condition/inadequate management. Nearly half (47%) of the vending sites did not have a handwashing facility, with soap and water available. Only 7% reported having any authority oversight of food safety. Food safety and hygiene practices in most cookri shops and restaurants was ‘poor’ with very limited surveillance system in place by competent authorities for compliance of food operators. Hand washing, clean surroundings, and covered food were the most common and emphasized practices to mitigate the risks associated with unsafe food. 展开更多
关键词 Food Safety and Hygiene Formal and Informal Food Vendors Western Area sierra Leone
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Cenozoic Age Counterclockwise Rotation in the Northwest End of the Sierras Pampeanas, Argentina
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作者 Adolfo Antonio Gutiérrez Ricardo Mon +2 位作者 Clara Eugenia Cisterna Uwe Altenberger Ahmad Arnous 《Open Journal of Geology》 CAS 2023年第5期345-383,共39页
Investigations into the Andean orocline revealed a counterclockwise rotation of about 37° in the north and a clockwise rotation of about 29° in the south. This rotation would have started in the Eocene becau... Investigations into the Andean orocline revealed a counterclockwise rotation of about 37° in the north and a clockwise rotation of about 29° in the south. This rotation would have started in the Eocene because the Nazca and South American plates converged. The transition zone between the Puna and the Sierras Pampeanas has a clockwise rotation pattern. Our new data show that the NE convergence of the Nazca and South American plates caused the counterclockwise rotation around the NW end of the Sierras Pampeanas. The temperature rise during a magmatic activity at 13 Ma would have favored a counterclockwise rotation of the mountain blocks of about 20° on a detachment zone within 10 to 15 km of depth. These range rotations generated local stress tensors trending NE and NW, facilitating the development of valleys, basins, mineralized dikes, mineral deposits, and alluvial fans separated from their origin. The Atajo fault shows both ductile and brittle characteristics. A mylonitic belt from the Sierra de Aconquija was juxtaposed on the rocks of the Ovejería Block and the Farallón Negro Volcanic Complex by reverse vertical displacement, and a dextral horizontal component of displacement resulted in curvatures that gave rise to pull-apart basins and step over features. The Santa Maria Valley, Campo del Arenal, Hualfín Valley, and Pipanaco salt flat most likely constituted a vast early Miocene basin rarely interrupted by low feature relief. 展开更多
关键词 NEOTECTONIC Counterclockwise Rotation ANDES sierras Pampeanas Transcurrent Faults Morphotectonic
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Environment and Awareness Influencing Food Safety in the Western Area, Sierra Leone
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作者 Philip John Kanu Hamid Turay +1 位作者 Abdulai Kandeh Mary Hodges 《Food and Nutrition Sciences》 2023年第11期1013-1030,共18页
Food safety, nutrition, health and wellbeing are inextricably linked. This study investigated the environmental, awareness and practices amongst both food vendors and consumers in and around Freetown the capital of Si... Food safety, nutrition, health and wellbeing are inextricably linked. This study investigated the environmental, awareness and practices amongst both food vendors and consumers in and around Freetown the capital of Sierra Leone. The population of the area has vastly out-grown the infrastructure laid down before and since independence. De-centralization of authority to local councils as recommended post-war has only been partial. The role of local versus central government in the planning and maintenance of water, sanitation and market-infrastructure and related policies was explored. This is a qualitative study that used semi-structured interviews with vendors, consumers and 29 key informants. Amongst an estimated population of 5386 actors in food services a sample size of 309 vendors, consumers in and around the 12 busiest market hubs in Western Area Urban and Rural Districts were sampled. Most of the respondents described “food safety” as “good-to-eat, well taken care-off, and free from germs”. The respondents cited that main causes to unsafe food are poor hygienic practices: 38%, contamination by flies: 28%, uncovered food/ improper handling/poor personal hygiene: 21%, and environmental factors, such as improper refuse disposal: 11%. Respondents expressed that consuming unsafe foods can lead to diarrhoea: 34%, food poisoning: 24%, vomiting: 17%, stomach ache/pain: 16%, or typhoid: 9%. Various measures to improve food safety were cited as hand washing: 60%, cleaning surroundings: 57%, covering food: 56%, washing utensils: 52%, covering hair: 42% and using a face mask: 32%. However almost 76% of food vendors interviewed were trading near gutters, where muddy/dirty water settled, with slippery floors, discarded plastic waste, flies and inadequate water, sanitation, and/or storage facilities. None of the food vendors had had any formal training on food safety. Despite progress recently made in solid and liquid waste management during the “Transform Freetown” agenda much more improvement in infrastructure and behaviour change is required. Similarly, despite improvements in formal market facilities the pattern of informal street trading remains the most prevalent especially for the poor. The link between “safe food” and good health was only partially understood, whilst the widespread application of recommended practices to reduce risks was lacking due in part to inadequate infrastructure. As the importance of food safety becomes better understood by administrators and the public the investments required in infrastructure and social and behavioural change will contribute towards a healthier environment and outcomes. 展开更多
关键词 Food Safety Freetown sierra Leone Water and Sanitation HYGIENE
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Changes in Rainfall and Temperature and Its Impact on Crop Production in Moyamba District, Southern Sierra Leone
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作者 Keiwoma Mark Yila Mathew Lamrana Siaffa Gboku +1 位作者 Mohamed Sahr Lebbie Lamin Ibrahim Kamara 《Atmospheric and Climate Sciences》 CAS 2023年第1期19-43,共25页
Rainfall and temperature are the important variables that are often used to trace climate variability and change. A Perception study and analysis of climatic data were conducted to assess the changes in rainfall and t... Rainfall and temperature are the important variables that are often used to trace climate variability and change. A Perception study and analysis of climatic data were conducted to assess the changes in rainfall and temperature and their impact on crop production in Moyamba district, Sierra Leone. For the perception study, 400 farmers were randomly selected from Farmer-Based Organizations (FBOs) in 4 chiefdoms and 30 Agricultural Extension Workers (AWEs) in the Moyamba district were purposely selected as respondents. Descriptive statistics and Kendall’s test of concordance was used to analyze the data collected from the farmers and AEWs. Data for the analysis of variability and trends of rainfall and temperature from 1991 to 2020 were obtained from the Sierra Leone Meteorological Agency and Njala University and grouped into monthly, seasonal and annual time series. Regression analyses were used to determine the statistical values and trend lines for the seasonal and annual time series data. The Mann-Kendall test and Sen’s Slope Estimator were used to analyze the significance and magnitude of the trends respectively. The results of both studies show evidence of climate change in the Moyamba district. A substantial number of farmers and AEWs perceived a decrease in the annual rainfall amount, length of the rainy season, a late start and end of the rainy season, an increase in the temperature during the day and night, and a shortened harmattan period over the last 30 years. Analysis of the meteorological data shows evidence of variability in the seasonal and annual distribution of rainfall and temperature, a decreasing and non-significant trend in the rainy season and annual rainfall and an increasing and significant trend in seasonal and annual temperature from 1991 to 2020. However, the observed changes in rainfall and temperature by the farmers and AEWs partially agree with the results of the analyzed meteorological data. The majority of the farmers perceived that;adverse weather conditions have negatively affected crop production in the district. Droughts, high temperatures, and irregular rainfall are the three major adverse weather events that farmers perceived to have contributed to a substantial loss in the yields of the major crops cultivated in the district. In response to the negative effects of adverse weather events, a substantial number of farmers take no action due to their lack of knowledge, technical or financial capacity to implement climate-sensitive agricultural (CSA) practices. Even though few farmers are practicing some CSA practices on their farms, there is an urgent need to build the capacity of farmers and AEWs to adapt to and mitigate the negative impacts of climate change. The most priority support needed by farmers is the provision of climate-resilient crop varieties whilst the AEWs need training on CSA practices. 展开更多
关键词 Climate Change RAINFALL Temperature Farmer’s Perception Crop Productivity sierra Leone
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Radio Direction Finding Method to Mitigate Tsunami Risk in Sierra Leone
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作者 Valentino Straser Daniele Cataldi Gabriele Cataldi 《Advances in Geological and Geotechnical Engineering Research》 2023年第2期64-75,共12页
In this study,the Radio Direction Finding method is proposed for the detection of electromagnetic signals,in the VLF band,to try to anticipate the occurrence of potentially destructive geophysical events.The experimen... In this study,the Radio Direction Finding method is proposed for the detection of electromagnetic signals,in the VLF band,to try to anticipate the occurrence of potentially destructive geophysical events.The experimentation concerns the interception of electromagnetic anomalies in Sierra Leone,in the five-day time window,associated with seismic events that could potentially generate tsunamis.The area of investigation is Sierra Leone,whose coastline is subjected to tidal wave hazards triggered by earthquakes generated in the Mid-Atlantic Ridge.Although Sierra Leone is not affected by recurrent earthquakes,there is nevertheless a low probability,estimated at 2 percent,of the occurrence of destructive earthquakes in the next 50 years.Also in estimates,the risk of rogue and potentially damaging waves is estimated to strike the Sierra Leone coast at least once in the next 10 years.The Radio Direction Finding experiment carried out continuously 24/7,has shown a close relationship between increased radio-anomalies,in the frequencies of 6,000 Hz,a time window between electromagnetic anomaly detection and the imminence of an earthquake,and higher frequency times for the risk of earthquake occurrence in the Mid-Atlantic Ridge. 展开更多
关键词 TSUNAMI Radio direction finding Destructive earthquakes Mid-Atlantic ridge sierra Leone
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基于实证分析的下一代图书馆服务平台选择策略——以ALAM、Kuali OLE、OCLC WorldShare和Sierra为例 被引量:24
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作者 李娟 张雪蕾 杨峰 《图书与情报》 CSSCI 北大核心 2017年第3期84-92,共9页
目前国内外图书馆已对部分主流商业和开源的下一代图书馆服务平台实施部署应用或功能研究,探索目前主要应用的图书馆集成系统如何向下一代图书馆服务平台转型及过渡。文章通过针对我国图书馆集成管理系统面临的现状,结合层次分析法和专... 目前国内外图书馆已对部分主流商业和开源的下一代图书馆服务平台实施部署应用或功能研究,探索目前主要应用的图书馆集成系统如何向下一代图书馆服务平台转型及过渡。文章通过针对我国图书馆集成管理系统面临的现状,结合层次分析法和专家论证,构建了下一代图书馆服务平台评价指标体系,并对市场上主流的ALAM、Kuali OLE、OCLC WorldShare和Sierra四类下一代图书馆服务平台进行评估,最后通过评估结果与工作实践,为我国下一代图书馆服务平台的选择提出了若干策略。 展开更多
关键词 下一代图书馆服务平台 选择策略 图书馆集成系统 ALAM Kuali OLE OCLC WorldShare sierra
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下一代图书馆服务平台Sierra和Alma的比较研究——基于Marshall Breeding 2016年调查数据 被引量:7
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作者 李娟 张雪蕾 魏青山 《现代情报》 CSSCI 北大核心 2017年第6期113-118,共6页
本文首先概括了图书馆服务平台的技术和功能特征,并介绍了目前主流的图书馆服务平台,重点基于Marshall Breeding 2013-2016年相关调研用户反馈结果和统计数据,从用户对系统满意度、系统功能性、印刷型馆藏管理功能、电子资源管理功能、... 本文首先概括了图书馆服务平台的技术和功能特征,并介绍了目前主流的图书馆服务平台,重点基于Marshall Breeding 2013-2016年相关调研用户反馈结果和统计数据,从用户对系统满意度、系统功能性、印刷型馆藏管理功能、电子资源管理功能、公司满意度、支持满意度、支持改进、公司忠诚度和开源兴趣等9个方面对Alma和Sierra两项产品进行多维分析与比较,期望为国内图书馆评估和选择LSP产品时提供参考与借鉴。 展开更多
关键词 图书馆 服务平台 图书馆集成系统 Alma sierra
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SIERRA热式气体质量流量计应用实践 被引量:1
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作者 黄承光 任文慧 《计量技术》 北大核心 2000年第7期44-44,共1页
关键词 sierra热式气体质量流量计 原理 技术特点 应用
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Next-generation Sequencing Study of Pathogens in Serum from Patients with Febrile Jaundice in Sierra Leone 被引量:2
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作者 ZHANG Yi YE Fei +11 位作者 XIA Lian Xu ZHU Ling Wei IDRISSA Laybohr Kamara HUANG Ke Qiang ZHANG Yong LIU Jun BRIMA Kargbo WANG Ji LIANG Mi Fang SONG Jing Dong MA Xue Jun WU Gui Zhen 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2019年第5期363-370,共8页
Objective People in Western Africa suffer greatly from febrile jaundice, which is caused by a variety of pathogens. However, yellow fever virus(YFV) is the only pathogen under surveillance in Sierra Leone owing to the... Objective People in Western Africa suffer greatly from febrile jaundice, which is caused by a variety of pathogens. However, yellow fever virus(YFV) is the only pathogen under surveillance in Sierra Leone owing to the undeveloped medical and public health system there. Most of the results of YFV identification are negative. Elucidation of the pathogen spectrum is required to reduce the prevalence of febrile jaundice. Methods In the present study, we used Ion Torrent semiconductor sequencing to profile the pathogen spectrum in archived YFV‐negative sera from 96 patients in Sierra Leone who presented with unexplained febrile jaundice. Results The most frequently identified sequencing reads belonged to the following pathogens: cytomegalovirus(89.58%), Epstein‐Barr virus(55.21%), hepatitis C virus(34.38%), rhinovirus(28.13%), hepatitis A virus(20.83%), coxsackievirus(10.42%), Ebola virus(8.33%), hepatitis E virus(8.33%), lyssavirus(4.17%), leptospirosis(4.17%), chikungunya virus(2.08%), Crimean‐Congo hemorrhagic fever virus(1.04%), and hepatitis B virus(1.04%). Conclusion The distribution of sequencing reads suggests a broader spectrum of pathogens for consideration in clinical diagnostics and epidemiological surveillance in Sierra Leone. 展开更多
关键词 sierra Leone FEBRILE JAUNDICE Next‐generation SEQUENCING VIRUS
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Probabilistic Rainfall Thresholds for Landslide Episodes in the Sierra Norte De Puebla, Mexico 被引量:1
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作者 Alejandra González Ernesto Caetano 《Natural Resources》 2017年第3期254-267,共14页
The Sierra Norte de Puebla, Mexico, has a record of hundreds of mass removal processes triggered by rainfall, where the intensity and duration of the rain are the main mechanisms. In order to determine threshold value... The Sierra Norte de Puebla, Mexico, has a record of hundreds of mass removal processes triggered by rainfall, where the intensity and duration of the rain are the main mechanisms. In order to determine threshold values for precipitation as a cause of a landslide, the prior, marginal and conditional probabilities were calculated. A Bayesian method was used for one-dimensional (precipitation intensity) and two-dimensional (precipitation intensity and duration) analysis. This suggested a high probability of mass movement when the precipitation exceeds 60 mm within ten days. A proposed warning system is based on classes in which the threshold is exceeded. 展开更多
关键词 Processes of Mass Removal Thresholds Probability BAYESIAN Method sierra NORTE DE PUEBLA
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Detection and Analysis of Ebola Virus in Sierra Leone-China Friendship Biosafety Laboratory from March 11 to April 20, 2015 被引量:2
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作者 WANG Qin ZHANG Yong +13 位作者 WANG Huan Yu DU Hai Jun NIE Kai SONG Jing Dong XIAO Kang LEI Wen Wen GUO Jian Qiang WEI He Jiang CAI Kun WANG Yan Hai WU Jiang Gerald BANGURA Idrissa Laybohr KAMARA DONG Xiao Ping 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2016年第6期443-447,共5页
Ebola virus disease reemerged in Western Africa in 2014.Chinese Center for Disease Control and Prevention dispatched the first Ebola virus(EBOV)detection team to run newly established Sierra Leone-China Friendship B... Ebola virus disease reemerged in Western Africa in 2014.Chinese Center for Disease Control and Prevention dispatched the first Ebola virus(EBOV)detection team to run newly established Sierra Leone-China Friendship Biological Safety Laboratory.The aims of study were to understand epidemiology,clinical manifestations and survival time of EBOV in patient's blood.A total of 913specimens were tested between March 11 and April20, 2015. EBOV positivity occurred in 7.37% of the blood and 0.53% in throat swabs. 展开更多
关键词 Detection and Analysis of Ebola Virus in sierra Leone-China Friendship Biosafety Laboratory from March 11 to April 20 2015 EVD
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The Impact of Cattle Grazing in High Elevation Sierra Nevada Mountain Meadows over Widely Variable Annual Climatic Conditions 被引量:1
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作者 Lindsey Myers Brenda Whited 《Journal of Environmental Protection》 2012年第8期823-837,共15页
The impact of summer cattle grazing on water quality during three very different climatic years in the Sierra Nevada was investigated. Water year 2009 had near normal precipitation;2010 had late precipitation and snow... The impact of summer cattle grazing on water quality during three very different climatic years in the Sierra Nevada was investigated. Water year 2009 had near normal precipitation;2010 had late precipitation and snowmelt;and 2011 had 150% above normal precipitation. Surface waters were tested for pathogenic bacteria indicators fecal coliform, E. coli, and total coliform before and after cattle were released onto summer grazing allotments. Water samples were collected from meadow stream sites up to 6 weeks before and up to 6 weeks after cattle grazing began. Streams passing through ungrazed meadow served as controls. Eight sample sites were between 1694 m and 2273 m in elevation;one site was lower at 1145 m in elevation. Samples were transported within 6 hours to a water analysis laboratory, where samples were analyzed following standardized laboratory methods. Results showed that individual site and total mean concentrations of E. coli in surface waters were within regulatory standards before cattle arrived during each of the 3 study years. After the beginning of grazing, mean E. coli counts increased as follows: 2009 from 8 to 240 CFU/100mL, 2010 from 7 to 561 CFU/10mL;2011 from 7 to 657 CFU/100mL (p < 0.05 all years). Total coliform bacteria and fecal coliform concentrations showed the same pattern. This study shows that cattle grazing in the high elevation Sierra Nevada results in a significant increase in indicator bacteria. This impact on the watersheds occurs despite widely variable annual climatic conditions. 展开更多
关键词 Water Quality sierra NEVADA Mountain MEADOWS LIVESTOCK GRAZING CATTLE Indicator Bacteria
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Comprehensive Assessment of Groundwater Quality around a Major Mining Company in Southern Sierra Leone
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作者 Rex-Edwin M. Massally Abu Bakarr Sheriff +3 位作者 Daniel Kaitibi Alfred Abu Mariatu Barrie Eldred Tunde Taylor 《Journal of Water Resource and Protection》 2017年第6期601-613,共13页
Ensuring availability and sustainable management of water and sanitation for all by 2030 is Goal 6 of the Sustainable Development Goals (SDGs). Since developing countries especially in Africa would struggle to meet th... Ensuring availability and sustainable management of water and sanitation for all by 2030 is Goal 6 of the Sustainable Development Goals (SDGs). Since developing countries especially in Africa would struggle to meet this target, this study was conceived. Hence, the study was designed to assess the water quality for physiochemical parameters around a mined out site in southern Sierra Leone with the view to determine their levels, determine related associations among indicators and explore environmental forensic options. A finite population correction factor was used to identify fifty (50) groundwater sources from one hundred and fifty two (152) in nine (9) sections of Moriba Town, in Moyamba District, Sierra Leone which constitute the sample size. The study assessed sixteen (16) physical and chemical indicators across the defined boundary of the sample size. Results indicated that almost 80% of all the indicators were in good agreement with water quality standards with the exception of three. Turbidity correlated strongly with , Al and ?and almost all other indicators did not show meaningful association. High values with significant variance of water quality indicators of physical to chemical ratio were observed for pH, temperature, electrical conductivity (EC) and total dissolved solids (TDS) but no such observation was noted for turbidity. On the whole, the water quality was judged to be good, although more pro active actions were encouraged by the local people and the mining company so as to reduce contamination in some areas. 展开更多
关键词 GROUNDWATER Water Quality PHYSICO-CHEMICAL MINING Area sierra Leone
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Strategies for Promoting Rice Self-sufficiency in Sierra Leone
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作者 Alphajoh Alhadi Bah 《Journal of Northeast Agricultural University(English Edition)》 CAS 2013年第4期78-86,共9页
Rice is the main food of Sierra Leoneans and an important source of employment and income for rural communities. According to the West African Rice Development Association report, annual consumption of rice is amongst... Rice is the main food of Sierra Leoneans and an important source of employment and income for rural communities. According to the West African Rice Development Association report, annual consumption of rice is amongst the highest in SubSaharan Africa(SSA), 104 kg. Mainly, small scale farmers who are resource poor on both the upland and various lowlands grow rice. Sierra Leone has not been able to produce enough rice to meet its local consumption demand for a very long time now. 530 000 MT of milled rice is the required consumption need of the Sierra Leonean population per annum. In 2007, national paddy rice production was projected at 638 000 MT. The level of rice self-sufficiency rose from 50.57% in 2002 to 62.15% in 2006 and then to 63.49% in 2007. The remainder must be imported at increasingly expensive prices in the current situation of high food prices, which includes rice. The price of rice has seen a steady increase in the entire country. What most affected by this, is the low-income urban and peri-urban households. The promotion of domestic rice production is therefore a key element in the strategies for improving rice self-sufficiency, stimulating economic growth and increasing rural income. Therefore, supporting rice production programme is the only solution to pull the country out of the worsening rice situation and maintain the present trend in rice self-sufficiency. Therefore, having an understanding of the strategic interventions in rice production in Sierra Leone is an important ingredient in the promotion and attainment of rice self-sufficiency. 展开更多
关键词 STRATEGY rice production SELF-SUFFICIENCY sierra Leone
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Butterfly Assemblages of Two Wetlands: Response of Biodiversity to Different Environmental Stressors in Sierra Leone
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作者 Rosina Kyerematen Fatmata Kaiwa +2 位作者 Daniel Acquah-Lamptey Samuel Adu-Acheampong Roger Sigismond Andersen 《Open Journal of Ecology》 2018年第7期379-395,共17页
In a bid to enhance the integrity and health of selected network of ecosystems and effectively manage them in Sierra Leone, a baseline assessment of butterfly diversity of two wetland ecosystems Mamunta Mayosso Wildli... In a bid to enhance the integrity and health of selected network of ecosystems and effectively manage them in Sierra Leone, a baseline assessment of butterfly diversity of two wetland ecosystems Mamunta Mayosso Wildlife Santuary (MMWS) and Sierra Leone River Estuary (SLRE) affected by different environmental stressors was undertaken as part of the Sierra Leone Wetland Conservation Project (SLWCP). We hypothesised that different environmental stressors affect butterfly communities in wetlands in Sierra Leone and the higher the stress the lower the butterfly diversity in an area. Sampling was conducted via field identification by wing patterns, flight mode, direct counts along transects and charaxes trapping. A total of 2300 individuals representing 95 species of butterflies were recorded. Though butterflies were evenly distributed at both sites, MMWS recorded the highest richness and abundance of butterflies during both seasons. This observation is reported to be because of high environmental stressors such as mining, agriculture and pollution from factories in the SLRE. The results further show that MMWS is made up of a mosaic of different vegetation patches that support higher diversity of butterfly species. This study also reveals that anthropogenic activities have a negative impact on butterfly diversity. 展开更多
关键词 BIODIVERSITY Butterflies ENVIRONMENT sierra Leone WETLANDS
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加利福尼亚洲Sierra Nevada中部西变质带地体的区域构造和应变分析
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作者 S.R.Paterson 潘云泽 《世界地质》 CAS CSCD 1990年第4期46-70,共25页
Sierra Nevada西变质带225个全应变样品的比较表明,应变类型与强度取决于岩石类型。杂砂岩和碎屑支撑砾岩应变最小,而强应变则出现于火山砾凝灰岩、含砾泥灰岩和板岩中。大的火山岩带为面型应变,而其附近的板岩和杂砂岩序列则表现为压... Sierra Nevada西变质带225个全应变样品的比较表明,应变类型与强度取决于岩石类型。杂砂岩和碎屑支撑砾岩应变最小,而强应变则出现于火山砾凝灰岩、含砾泥灰岩和板岩中。大的火山岩带为面型应变,而其附近的板岩和杂砂岩序列则表现为压扁型应变,表明在板岩中有40%~65%的体积损失,杂砂岩中有0~26%的体积损失,火山砾凝灰岩中体积损失为11%。不同岩石类型之间体积损失和应变的差异要求在大多数岩性界面上存在总应变的不连续。在西变质带范围内,岩性、区域构造样式和应变场的彼此独立,表明可以固定出三个地体(Foothills,Merced River和Northern Sierra)和两个特征的构造域(东、西Foothills地体)。这些地体周围为大的韧性剪切带所环绕,在平均应变强度和方向方面有差异,这种差异不是在应变类型方面。在Foothills地体中,应变强度从Foothills西部带的中强减小到Foothills东部带的较低值。在研究区内,应变强度在Melones和B(?)ar Mountai(?)s断裂带和Melons断裂带之东地体中最高。在各个地体中与区域变形有关的各种构造形迹并不能超越地体边界很大距离,因此,区域构造的多期迭加在西变质带研究区内是较为罕见的。在断裂带之外,我们在Foothills地体观测到一组更大一些的劈理面;在Northern Sierra地体则发现两组更早的劈理构造。但是,较晚的变形可使相邻地体内较早的构造活化和旋转。Foothlls地体内变形的运动学机制和时间表明断裂活动和刚性旋转发生于区域性缩短之前持续的断裂活动和断裂旋转成陡倾角。如果韧性构造带的方向代表板块运动,那么Merced River地体中的构造则表明该地体具有侏罗—第三纪时期的NNE向的正向消亡,而Foothills地体中的构造表明,约在150Ma之前。 展开更多
关键词 sierra NEVADA 变质带 区域构造 劈理 岩石类型 火山砾 杂砂岩 韧性剪切带 应变椭球体 侏罗
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Relict glacial landscape in the Sierra Baguales Mountain Range(50°-51°S):evidence of glaciation dynamics and types in the eastern foothills of the southern Patagonian Andes
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作者 ARAOS.JoséMiguel LE ROUX.Jacobus Philiphus GUTIERREZ.Néstor Mauricio 《Journal of Mountain Science》 SCIE CSCD 2017年第2期282-295,共14页
The glacial morphology of southern South American presents invaluable evidence to reconstruct former glacier behaviour and its relation to climate and environmental changes. However, there are still spatial and tempor... The glacial morphology of southern South American presents invaluable evidence to reconstruct former glacier behaviour and its relation to climate and environmental changes. However, there are still spatial and temporal gaps in the reconstruction of the Holocene Patagonian glacial landscape. Here we present the first geomorphological record for the Sierra Baguales Mountain Range(SBMR), forming the eastern foothills of the Southern Patagonian Andes 200 km from the Pacific coast. This area is topographically isolated from the Southern Patagonian Ice Field(SPIF), and is affected by the Westerly Winds. The study area shows evidence of ice sheet and alpine glaciations related to Andean uplift,which caused a marked climatic contrast between its western and eastern flanks since the Last Glacial Maximum(LGM). The regional rock mass strength and precipitation gradient acted as a controlling factor in the glacial cirque distribution and sizes, as well as in the development of glaciation types. We report new radiocarbon dates associated with warm/dry to cold/wet climatic changes during the middle Holocene, when former small alpine glaciers were located in the uppermost section of the SBMR basins, and eventually converged to form a small ice field or a composite valley glacier at lower elevations.This can be explained by an estimated regional temperature drop of 3.8°C±0.8°C, based on a 585±26m Equilibrium Line Altitude(ELA) descent, inferred by geomorphological evidence and the Accumulation Area Ratio(AAR), in addition to a free-air adiabatic lapse rate. Subsequently, the glaciers receded due to climatic factors including a rise in temperature, as well as non-climatic factors, mainly the glacier bedrock topography. 展开更多
关键词 Glacial morphology sierra Baguales Ice sheet glaciations Alpine glaciations Middle Holocene
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PMC—Sierra推出具有集成保护处理功能的240G交叉连接光纤IC
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《半导体技术》 CAS CSCD 北大核心 2003年第8期76-76,共1页
关键词 PMC—sierra公司 TSE240 交叉连接器 保护交换 MAPS
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The influence of price on rice production in Sierra Leone
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作者 Alhaji Mohamed Hamza Conteh Xiangbin Yan Foday Pinka Sankoh 《Agricultural Sciences》 2012年第4期462-469,共8页
Rice is the main staple food of the vast majority of Sierra Leoneans, eaten on a daily basis by almost every household in the country. Rice is the most important food crop widely grown by farmers across the country. A... Rice is the main staple food of the vast majority of Sierra Leoneans, eaten on a daily basis by almost every household in the country. Rice is the most important food crop widely grown by farmers across the country. Although much attention is now focused on rice production through the small holder commercialization programme (SHCP), less attention has been given to investigating the constraints faced by rice producers in the country. Also, as food insecurity continues to be a major development problem across the country, thereby undermining people’s health, productivity, and often their very survival;this study contributes to efforts to overcome the development challenges posed by food insecurity necessarily begin with accurate assessment of influential factors that constrained the production of the staple food, rice. The main objective of this study is therefore to analysis the factors that influence rice production in the country, and specifically examine the relationship between rice production and the price of rice as sold in the domestic market. The study used a log linear model with the quantity of rice produced as the dependent variable and the price of domestic rice, quantity of rice imported and price of imported rice as explanatory. Findings indicated that, domestic rice is more expensive than imported rice per ton, and this underscores the argument that, rice importation is undermining domestic rice production as a viable income generating activity. Also, almost all the people in the capital city which hosts about 70% of the total population of country prefer eating imported rice, since it is free from stones and other impurities. However, In order to control price and still increase rice production, the government should be able to purchase the rice from the farmers and then sell this rice to private retailers. 展开更多
关键词 sierra Leone FOOD SECURITY RICE Production Econometric Model Specification PRICE of DOMESTIC RICE
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Landscape Patterns of Vegetation Canopy Regrowth Following Wildfires in the Sierra Nevada Mountains of California
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作者 Christopher Potter 《Open Journal of Forestry》 2015年第7期723-732,共10页
Rapid recovery of pioneer shrub and forest patch cover can reduce soil erosion, nutrient runoff and degradation of stream habitats, and promote small mammal and avian biodiversity following stand-replacing wildfires. ... Rapid recovery of pioneer shrub and forest patch cover can reduce soil erosion, nutrient runoff and degradation of stream habitats, and promote small mammal and avian biodiversity following stand-replacing wildfires. Landsat imagery from the past 25+ years was analyzed to understand patterns and rates of vegetation recovery, focusing on high burn severity (HBS) patches, within wildfire areas dating from the late 1940s in the Sierra-Nevada region of California. Normalized difference vegetation index (NDVI) levels indicative of recovered woody cover within HBS areas were analyzed starting in 1985 to quantify regrowth of patch dynamics. Analysis of landscape metrics showed that the percentage of total HBS area comprised by the largest patch of recovered woody cover was relatively small in all fires that occurred since 1995, but increased rapidly with time since fire. Patch complexity of recovered woody cover decreased notably after more than 50 years of regrowth, but was not readily associated with time for fires that occurred since the mid 1990s. Patch complexity of dense woody cover was consistently high in fires after 1995 and increased with the elevation of HBS areas. The aggregation level of patches with recovery of woody cover increased steadily with time since fire. The study approach using satellite remote sensing can be expanded to assess the consequences of stand-replacing wildfires in all forests of the region. 展开更多
关键词 LANDSAT Forest WILDFIRE Regrowth DISTURBANCE sierra NEVADA California
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