22 research outputs found
Webometric Analysis of Linkages between Environment Related Researchers and Institutes in Sri Lanka
Get PDFEvery scientist, research Institute and all research publications are connected to one another by means of affiliations, co-authorships and citations. The objective of the present study was to visualize linkages among researchers and institutes in environment related publications in Sri Lanka, aiming to identify special patterns and trends. This Webometric and Bibliometric study had three main sections: co-citation analysis, co-authorship analysis, and hyperlink analysis. In addition, an author keyword analysis and a co-citation analysis was conducted to identify different areas within the environmental science field and their relative popularity. The analysis was conducted using data gathered from the abstract and citation database “Scopus”, which were published during the 10-year time period from 2006 to 2015.VOSviever was used to generate maps. Gathered data revealed that a total of 10,367 authors were involved in environment related publications. It has been observed that even though the study was conducted using Sri Lankan publications, collaboration between foreign and domestic scientists was higher than Sri Lankan scientists themselves. From subject related linkages within environment related publications, the study revealed 24 different subject areas of interest among scientists based on author keyword analysis and co-citation analysis. Out of that 13.3% and 11.9% of the publications are related to ‘Ecology’ and ‘Agriculture’ respectively. It was found that 45 institutes were involved in environment related publications. Analysis revealed that 42.0% of total citation links (Citation Analysis) and 30.9% of total co-authorship links (Co-authorship Analysis) belong to the University of Peradeniya. Citation analysis of authors revealed 3,116 authors (30.1%) with at least one citation link, and 7,251 (69.9%) authors with zero citation links. Highest (10.1%) non-domestic citation links were with United States scientists. Followed by India (6.5%) and Australia (6.3%).Hyperlink analysis revealed a low connectivity between institute web domains with only 11 out of 45 domains that contain more than 10 outgoing ‘url citations’ to one another. It was evident that the research output in subject areas such as Wildlife Management, Climate Change and Waste Management are much lower in comparison. These institutes and researchers need to keep a much higher web activity and connectivity in order to obtain a better online visibility.Keywords: Webometrics, Bibiliometrics, Co-citation, Co-authorship, Hyperlink analysi
Perception of, and adjustment to, drought hazard by farmers in southern SRI Lanka
Get PDFIn Sri Lanka, two thirds of the land mass lies within the Dry Zone where agriculture is the most important economic activity. In this climatic zone, rainfall is highly uncertain, seasonal, and limited to a few months. Consequently, the farmers in the area have to face drought as a natural hazard. This study focusses on how the farmers in the southern Dry Zone of Sri Lanka perceive drought as a hazard, the adjustments they make to reduce their vulnerability to droughts and how human behaviour affects the growing hazardousness of the study area. The results of this study show that the farmers in the study area have perceived drought as one of their major problems, and that the vulnerability to this natural phenomenon is growing as a result of the power abuse and environmental mismanagement of those high ranking people responsible. However, the farmers’ deeper understanding regarding their living environment (natural and man-made) has enhanced their power to combat the hazardous effects of droughts by way of a variety of adjustments. Considering and studying the above problems and issues the researcher has come to some conclusions and has put forward some suggestions, the most important of which, lie with changing the self-centered attitudes and activities of the powerful people in the direction of a socially and environmentally more sustainable and wholesome path
State of Disaster Risk Reduction at the Local Level: A report on the Patterns of Disaster Risk Reduction Actions at Local Level
Get PDFSome Results Concerning Asymptotic Distributions and Their Applications.
No full textThis thesis is being submitted to the Indian statistical Institute in support of the author\u27s application for the degree of doctor of philosophy. The thesis embodies research carried out by the author during the period 1958-1961 under the supervision of dr.R.R. Bahadur, Professor of statistics are the Indian Statistical Institute Calcutta.This thesis is concerned with development of a new method of establishing asymptotic distributions and the elaboration of some of its applications in several fields of statistics.The thesis consists of five chapters. Chapter I describes, in general terms, the various problems considered in the thesis. Chapter II Deals with the basic results concerning the convergence of joint distributions under assumptions about the convergence of marginal and conditional distributions. Chapter III is devoted to the applications of the result of chapter II to some problems in in statistical methods. Chapter IV and V deal with some applications to Regression Analysis. Chapter V also contains the results of some model sampling experiments, and tables for practical use.Earlier versions of some of the results of Chapter III have appeared as joint article with Dr. B. V. Sukhatme of the Indian Council of Agricultural Research, New Delhi, in Sankhya, 21 (1959) 289-298 (Ref. 49 ]). Some of the results of Chapter IV have appeared in Sankhya, Series ,A, 23(1961), 73-90. (Ref. ( 48 1.)The author wishes to express his sincere gratitude to Dr. R.R, Bahadur for his guidance and advice on the method of presentation of the material in the thesis, and to Dr. C. R. Rao, Professor and Head of the Division of Theoretical Research and Training, Indian Statistical Institute, for his constant encouragement. The author is indebted to the following members of the Indian Statistical Institute:to Sri Nikilesh Bhattacharya for his help in some modol sampling experiments and for his reading Chapters IN and V; to Sri G. Parthas are thy for his help in some model sampling experinents; and so Sri T. Krishnamurthi and to Sri Debdas Choudhuri for theircom putation of tables I, II, III and IV on the electronic computer. The author also wishes to express his gratitude to Sri K.R.parthasarathy of the Indian Statis tical Institute for procuring and translating N.V. Smirnovs article (Ref. [ 50 ], which necessitated a revision of an earlier version of Chapter III.The author also records his gratefulness to the Research and The Training School of Indian Statistical Institute for providing facilities for research. Thanks are due to Sri G.M. Das for his efficient typing of the Thesis
Coastal land use in the Maltese islands: a description and appraisal
Get PDFThe area of the Maltese Islands is 316 km , and with an official coastal length of 180 km(^2) possess a high ratio of coastal length to area. The physical properties of the coast include a highly indented and largely accessible coastline having a low sloping profile, on the north, east and south-east littoral of Malta, presenting inlets, bays and deep harbours. Most of the recreational, industrial and coastal residential areas are situated around these areas together with a wide range of fortifications and military defensive structures built as part of the coastal defensive network of Malta over the last five centuries. In contrast, the other parts of the coast, including Gozo, consists of a largely inaccessible coastline made up of cliffs and boulder scree slopes with the few indentations marking sandy beaches. These areas have a high aesthetic quality. The rapid pace of development over last half-century has witnessed an economic transformation from an economy based on British military spending to one based on the development of coastal areas for marine-related services, tourism and residential and second-home development. Coastal land use conflicts have intensified with economic development and as people have sought to make a more use of the coast. This thesis is concerned with the evaluation of the coastal land use in the Maltese Islands. A historical overview of the coast is first presented, then a methodology for the mapping, surveying and estimation of the land uses along the coastal zone of the Maltese Islands is developed. This is based on a number of coastal field surveys that the author participated in between 1989 and 1998. The coastal zone was divided into sixteen segments and mapping is covered by sixteen land uses. The main results were that coastal development was centred in areas where a high natural coastal indentation and good physical accessibility of the coast were present, these, in turn, gave rise to land use conflict. In addition, civil engineering works and modifications such as rock-cutting, jetties, breakwaters and, in densely populated areas, promenades, intensified land use conflict. A notable difference in the type of coastal development processes to the north (tourism) and south (industry) of the Great Fault is evident. The thesis also includes the part played by the Malta Environment and Planning Authority in influencing coastal land uses, the main land use modifications proposed in the European Union accession talks and a brief assessment of the land use situation in selected localities in 2003
Molecular epidemiology and population genetics of "Plasmodium vivax" in Papua New Guinea
Get PDFAbstract: In recent years a new focus has been put on malaria, and elimination and eradication of this disease has been brought back to the agenda. While Plasmodium falciparum causes most of the disease in Africa, P. vivax is predominant in malaria endemic regions in Latin America, Asia and the South Pacific. In the last 10 years increasing reports of severe disease and even mortality caused by P. vivax raised new awareness for this parasite. Forty percent of the world population lives in areas of P. vivax transmission, and severe disease is caused especially in infants and young children. P. vivax has the ability to form semi-dormant liver hypnozoites that can relapse and lead to clinical disease after an extended period of time. As most currently applied drugs are not effective against hypnozoites, they present a mayor obstacle towards malaria control.
In the lowlands of Papua New Guinea (PNG), malaria prevalence reaches levels similar to those in sub-Saharan Africa. Both P. falciparum and P. vivax are frequent, and P. vivax reaches prevalence higher than anywhere else in the world. Individuals from these regions are often co-infected by both parasite species. Multiple concurrent infections with different strains of P. falciparum or P. vivax are common. For this thesis I have genotyped over 3000 P. vivax positive blood samples collected in a cohort study of 264 children. These children, aged 1 to 4.5 years, were followed over 16 months and visited every 8 weeks for collection of two blood samples taken 24 hours apart. Additional samples were collected whenever the children presented sick to the local health centre. In parallel morbidity data was collected. P. vivax was genotyped using two size polymorphic markers, which both distinguished individual parasite clones. Genotyping data of P. falciparum clones was available from a previous study.
Extensive diversity of the genotyping markers and high multiplicity of infection (MOI, the number of co-occurring clones per carrier) was observed. Each P. vivax positive child carried a mean of 2.7 concurrent infections, mean MOI was nearly twice as high as P. falciparum multiplicity in the cohort. We did not detect a seasonal trend in MOI, and only a moderate increase of MOI with age, most pronounced in very young children up to 3 years. Most likely relapses increase P. vivax mean MOI, and they also lead to high MOI during seasons of less transmission.
The detection of parasitemia in field surveys is imperfect owing to parasite densities below or fluctuating around the detection limit of light microscopy or PCR. We have compared >1000 pairs of samples collected 24 hours apart. The collection of a second sample was found to have a limited effect on parasite prevalence: a single PCR missed only 6 to 9% of the combined parasite positivity. The proportion of individual clones missed was more pronounced. Depending on the marker, 19% or 31% of all P. vivax clones were missed when sampling on a single day. As a consequence, mean MOI increased from 2.7 to 3.4 when combining results from paired samples. Detectability does not differ between P. vivax and P. falciparum or between age groups. Thus comparisons of prevalence and MOI between species and age trends are not biased by detectability.
To investigate structuring of P. vivax population in PNG, we have typed a subset of samples with 13 additional markers. Allele frequencies and haplotypes were compared to those from samples collected at other sites in PNG. No differences were detected between parasite populations, most likely because of high gene flow between sites. This is in contrast to the situation in countries of lower endemicity, and differs from the earlier observed moderate structuring in P. falciparum populations from PNG.
In this cohort study, the incidence of P. vivax malaria decreased with age, whereas the incidence of P. falciparum peaked later at the age of 3.5 years. These contrasting trends are in line with results from other countries were both parasites are co-endemic. Differences in the parasite biology, e.g. a more limited reservoir of surface antigens of P. vivax compared to P. falciparum, might cause faster immunization against P. vivax and thus the different age trends in incidence. But also differences in transmission intensity might be responsible. Our typing of clones over an extended period of time allowed estimations of the molecular force of infection (molFOI), i.e. the number of infections per child per year. Each child acquired 14 P. vivax clones per year, but only 6 P. falciparum clones. molFOI did not change with age, suggesting that acquired immunity builds up gradually with each new clone, leading to a decrease in P. vivax incidence over time. This does not rule out that biological differences between P. vivax and P. falciparum also play a role.
PNG is among the countries with the poorest health infrastructure and the highest prevalence of malaria. P. vivax prevalence is in some regions as high as P. falciparum prevalence. High MOI and molFOI, as well as high levels of gene flow imply great resilience of P. vivax towards antimalarial interventions. Fast acquisition of semi-immunity leads to a large number of asymptomatic P. vivax carriers, potentially contributing to transmission, and control is further complicated by relapses, occurring in the blood weeks or months after transmission from the mosquito. The high proportion of P. vivax will be a major challenge towards malaria control and elimination in PNG. ---------- Zusammenfassung: In den letzten Jahren erhielt die Krankheit Malaria neue Aufmerksamkeit, und ihre Ausrottung in einzelnen Ländern oder gar weltweit wird wieder als realistisches Ziel angesehen. Plasmodium falciparum verursacht die meisten Krankheitsfälle in Afrika, dagegen ist P. vivax der vorherrschende Parasit in Malariagebieten in Lateinamerika, Asien und dem Südpazifik. In den letzten zehn Jahren haben Forschungen gezeigt, dass P. vivax häufig schwere Krankheit bis hin zum tödlichen Verlauf verursachen kann, insbesondere bei Kleinkindern. Dadurch geriet der Parasit nach Jahren mit wenig Beachtung erneut in den Fokus der Forschung. Vierzig Prozent der Weltbevölkerung leben in Gebieten mit P.vivax-Übertragung. P. vivax hat die Fähigkeit, Ruhestadien zu bilden, welche längere Zeit nach der Übertragung zum erneuten Krankheitsausbruch führen können. Die meisten der heute vorhandenen Medikamente sind wirkungslos gegen Leberstadien, darum sind diese eine grosse Hürde auf dem Weg zur Bekämpfung von Malaria.
In tief liegenden Gebieten von Papua Neuguinea erreicht die Malariaprävalenz Werte ähnlich der in Afrika südlich der Sahara. P. falciparum wie auch P. vivax sind häufig, und die P. vivax Prävalenz ist höher als irgendwo sonst auf der Welt. Bewohner dieser Gegenden sind häufig gleichzeitig mit beiden Spezies infiziert, sowie mit verschiedenen Linien derselben Art. Für diese Arbeit wurden die P. vivax Stämme in über 3'000 positiven Blutproben analysiert, die im Rahmen einer Kohortenstudie mit 264 Kindern gesammelt wurden. Diese Kinder im Alter von 1 bis 4.5 Jahren wurden während 16 Monaten alle 2 Monate besucht um im Abstand von 24 Stunden zwei Blutproben zu sammeln. Zusätzliche Proben wurden gesammelt, wann immer ein Kind eines der Gesundheitszentren aufsuchte. Parallel dazu wurden alle Erkrankungen der Kinder registriert. P. vivax Stämme wurden aufgrund von zwei molekularen Markern, bei welchen sich die Allele in der Grösse unterscheiden, typisiert. Im Rahmen einer vorhergehenden Studie wurden die P. falciparum Stämme in der Kohorte typisiert.
Die gewählten Marker wiesen eine hohe Diversität auf, und die Multiplizität (die Anzahl verschiedener Stämme pro Träger) war hoch. Jedes infizierte Kind trug im Schnitt 2.7 P. vivax Stämme, dieser Wert ist fast doppelt so hoch wie derjenige von P. falciparum. Es gab keine saisonalen Unterschiede in der Multiplizität, und nur einen geringen Anstieg der Multiplizität mit dem Alter der Kinder; dieser war am deutlichsten in sehr jungen Kindern unter 3 Jahren. Es ist davon auszugehen, dass wiederausbrechende Leberstadien die Multiplizität erhöhen, dies auch während Jahreszeiten mit geringerer Übertragung durch Mücken.
In Feldstudien ist die Detektion von Parasiten häufig unvollständig, d.h. die Dichte eines Teils der Parasiten liegt unter der Nachweisgrenze von Mikroskopie oder molekularen Methoden wie PCR. Wir haben über 1000 Blutproben-Paare verglichen, welche im Abstand von 24 Stunden gesammelt wurden. Die zusätzliche zweite Blutprobe hatte einen eher geringen Einfluss auf die Prävalenz, mittels PCR wurden nur 6 bis 9% der Proben falsch negativ diagnostiziert. Der Anteil der Stämme, die in einer einzelnen Proben nicht detektiert wurden, war dagegen ausgeprägter. Je nach Marker wurden 19 oder 31% aller P. vivax Stämme, die an mindestens einem der 2 Tage nachgewiesen wurden, am Tag 1 nicht entdeckt. Als Folge stieg die Multiplizität von 2.7 auf 3.4 wenn die Resultate von beiden Tagen kombiniert wurden. Die Wahrscheinlichkeit, einen Stamm zu detektieren, unterscheidet sich nicht zwischen P. vivax und P. falciparum oder in verschiedenen Altersklassen, folglich werden Vergleiche der Prävalenz und Multiplizität nicht beeinflusst.
Um die Populationsstruktur von P. vivax in Papua Neuguinea zu untersuchen haben wir einen Teil der Proben aus unserer Kohorte mit 13 weiteren molekularen Markern untersucht. Die Allele-Frequenzen und die Haplotypen wurden verglichen mit den-jenigen von drei anderen Orten in Papua Neuguinea. Es wurden keine Unterschiede zwischen diesen Parasitenpopulationen festgestellt, sehr wahrscheinlich aufgrund eines häufigen genetischen Austauschs zwischen den Populationen. Im klaren Gegensatz dazu wurden in Gebieten mit geringer P. vivax Prävalenz ausgeprägte Unterschiede zwischen Populationen beobachtet, und in früheren Studien wurde auch eine moderat ausgeprägte Populationsstruktur von P. falciparum in Papua Neuguinea festgestellt.
Die Inzidenz von P. vivax, also die Anzahl Erkrankungen, nahm in der Kohorte mit dem Alter deutlich ab, dagegen stieg die P. falciparum Inzidenz bis zu einem Alter von 3.5 Jahren. Diese gegensätzlichen Trends bestätigen Beobachtungen aus anderem Gebieten, wo beide Parasiten endemisch sind. Als mögliche Ursache kommen Unterschiede in der Biologie der Parasiten in Frage, z.B. eine kleinere Diversität von Oberflächenproteinen von P. vivax, wodurch die Immunisierung schneller verlaufen sollte. Auch sind Unterschiede in der Übertragungsrate von P. vivax und P. falciparum möglich. Unsere Typisierung von Stämmen über einen längeren Zeitraum ermöglicht, die „molekulare Infektionshäufigkeit“ zu bestimmen, also die Anzahl Infektionen pro Kind pro Jahr. Jedes Kind wurde im Schnitt mit über 14 P. vivax-Stämmen pro Jahr infiziert, aber nur mit etwa 6 P. falciparum-Stämmen. Die Infektionshäufigkeit änderte sich nicht mit dem Alter, dies lässt darauf schliessen, dass die Kinder mit der Zeit allmählich Immunität erlangten, und dadurch die Anzahl Erkrankungen zurückging. Dies schliesst natürlich nicht aus, dass auch Unterschiede in der Biologie eine Rolle spielt im Erlangen von Immunität.
Papua Neuguinea ist eines der Länder mit dem schlechtesten Gesundheitswesen und gleichzeitig einem hohen Auftreten von Malaria. Die Prävalenz von P. vivax ist manchen Gegenden gleich hoch wie diejenige von P. falciparum. Die hohe Multiplizität und Infektionshäufigkeit, wie auch der hohe Grad von genetischem Austausch zwischen Parasitenpopulationen, lässt auf einen hohen Widerstandsgrad gegenüber Massnahmen zur Malariakontrolle schliessen. Die schnelle Immunisierung gegen P. vivax führt dazu, dass es eine grosse Zahl von asymptomatischen Trägern gibt, die vermutlich immer noch zur Übertragung beitragen. Die Bekämpfung von P. vivax wird weiter erschwert durch die Leberstadien, welche noch Wochen oder Monate nach der Übertragung zu Krankheitsausbrüchen führen können. Der hohe Anteil von P. vivax an allen Malariafällen wird Papua Neuguinea vor grosse Herausforderungen stellen auf dem Weg zur Kontrolle und Elimination von Malaria
Checklist of the mosses of sub-Saharan Africa
No full text2939 moss taxa are listed for sub-Saharan Africa and adjacent islands, with distribution by country. Each distribution record is supported by a literature reference. The following new combinations are made: Calyptrochaeta cristata (Hedw.) O’Shea, Groutiella elimbata (Thér) O’Shea, Meiothecium undulatum (Ren. & Card.) O’Shea, Orthodontium ruwenzorensis (Thér. & Nav.) O’Shea, Pohlia lacouturei (Thér.) O’Shea, Sematophyllum corticolum (Aongstr.) O’Shea, Sematophyllum dixonii (Thér.) O’Shea, Sematophyllum nanopyxis (Geh.) O’Shea, Sematophyllum rigescens (Card.) O’Shea, and Thamnobryum malgachum (Card.) O’Shea
The Second International Symposium on Tilapia in Aquaculture
Get PDFProceedings of the symposium held in 1987 in Bangkok, Thailand, by tilapia scientists to discuss strategies for future research and development in the tilapia industry worldwide. Contains 82 full papers, 17 poster abstracts and author and species indexes. The full papers were presented under 7 sessions: culture systems, management and production; pathology; genetics and reproduction; nutrition, physiology; biology and ecology; and economics and socioeconomics.Tilapia culture, Conferences
Returns to investment in education : a further update
Get PDFReturns to investment in education based on human capital theory have been estimated since the late 1950s. In the 40-plus year history of estimates of returns to investment in education, there have been several reviews of the empirical results in attempts to establish patterns. Many more estimates from a wide variety of countries, including over time evidence, and estimates based on new econometric techniques, reaffirm the importance of human capital theory. The suthors review and present the latest estimates and patterns as found in the literature at the turn of the century. However, because the availability of rate of return estimates has grown exponentially, the authors include a new section on the need for selectivity in comparing returns to investment in education and establishing related patterns.Curriculum&Instruction,Teaching and Learning,Public Health Promotion,Decentralization,Economic Theory&Research,Agricultural Knowledge&Information Systems,Health Monitoring&Evaluation,Economics of Education
Endemic diseases and agricultural productivity: Challenges and policy response
Get PDFContrary to Asian countries, the agricultural sector in Africa had not benefited from the green revolution success. After a long time of disinterest in the agriculture sector in Africa, several voices arise now in favour of greater efforts towards this sector. Several studies tend to show the crucial role of agriculture in African countries’ growth and highlight the huge need of increasing the productivity in this sector. If increase in agriculture productivity requires both an expansion of irrigated areas and the adoption of high yield varieties, those innovations and their high development could be the source of negative health (and environmental) effects. Using a mega-analysis, this paper highlights first the links between health, disease and development and then agricultural productivity. The literature review shows that the negative effect of bad health was not systematically checked, and that the intensity of this effect depends of the disease, but also of the work productivity and the existence or not of a coping process. The second part of the paper focused on the development of high intensive agriculture as a risk factor for farmers’ and rural inhabitants’ health. This survey shows that whether irrigation and fertilizer and pest intensive use could be considered as highly health (and environmental) risk factors, appropriate control measures (such as for examples systematic maintenance of irrigation canals, alternate wetting and drying of irrigated fields or integrated pest management) considerably reduce this risk, while at the same time, increase the agriculture productivity.agriculture, productivity, endemic disease, health risk factor, Africa
