Traditional medicinal uses and biological activities of some plant extracts of African Combretum Loefl., Terminalia L. and Pteleopsis Engl. species

In Africa various species of Combretum, Terminalia and Pteleopsis are used in traditional medicine. Despite of this, some species of these genera have still not been studied for their biological effects to validate their traditional uses. The aim of this work has been to document the ethnomedicinal uses of several species of Combretum and Terminalia in Mbeya region, south-western Tanzania, and to use this information for finding species with good antimicrobial and cytotoxic potential. During a five weeks expedition to Tanzania in spring 1999 sixteen different species of Combretum and Terminalia, as well as Pteleopsis myrtifolia were collected from various locations in the districts of Mbeya, Iringa and Dar-es-Salaam. Traditional healers in seven different villages in the Mbeya region were interviewed in Swahili and Nyakyusa on the medicinal uses of Combretum and Terminalia species shown to them. A questionnaire was used during the interviews. The results of the interviews correlated well between different villages, the same species being used in similar ways in different villages. Of the ten species shown to the healers six were frequently used for treatment of skin diseases, bacterial infections, diarrhea, oedema and wounds. The dried plants were most commonly prepared into hot water decoctions or mixed into maize porridge, Ugali. Infusions made from dried or fresh plant material were also common. Wounds and topical infections were treated with ointments made from the dried plant material mixed with sheep fat. Twenty-one extracts of six species of Combretum and four of Terminalia, collected from Tanzania, were screened for their antibacterial effects against two gram-negative and five gram-positive bacteria, as well as the yeast, Candida albicans, using an agar diffusion method. Most of the screened plants showed substantial antimicrobial activity. A methanolic root extract of T. sambesiaca showed the most potent antibacterial effects of all the plant species screened, and gave a MIC value of 0.9 mg/ml against Enterobacter aerogenes. Also root extracts of T. sericea and T. kaiserana gave excellent antimicrobial effects, and notably a hot water extract of T. sericea was as potent as extracts of this species made from EtOH and MeOH. Thus, the traditional way of preparing T. sericea into hot water decoctions seems to extract antimicrobial compounds. Thirty-five extracts of five species of Terminalia, ten of Combretum and Pteleopsis myrtifolia were screened for their antifungal effects against five species of yeast (Candida spp.) and Cryptococcus neoformans. The species differed from each other to their antifungal effects, some being very effective whereas others showed no antifungal effects. The most effective extracts showed antifungal effects comparable to the standard antibiotics itraconazol and amphotericin B. Species of Terminalia gave in general stronger antifungal effects than those of Combretum. The best effects were obtained with methanolic root extracts of T. sambesiaca, T. sericea and T. kaiserana, and this investigation indicates that decoctions of these species might be used for treatment of HIV-related fungal infections. Twenty-seven crude extracts of eight species of Combretum, five of Terminalia and Pteleopsis myrtifolia were evaluated for their cytotoxic effects against human cancer cell lines (HeLa, cervical carcinoma; MCF 7, breast carcinoma, T 24 bladder carcinoma) and one endothelial cell line (BBCE, bovine brain capillary endothelial cells). The most outstanding effects were obtained with a leaf extract of Combretum fragrans, which nearly totally inhibited the proliferation of T 24 and HeLa cells at a concentration of 25 ug/ml and inhibited 60 % of the growth of the HeLa cells at a concentration of 4.3 ug/ml. The species of Terminalia were less cytotoxically potent than the Combretum species, although T. sericea and T. sambesiaca gave good cytotoxic effects (< 30 % proliferation). In summary this study indicates that some of the species of Terminalia, Combretum and Pteleopsis, used in Tanzanian traditional medicine, are powerful inhibitors of both microbial and cancer cell growth. In depth studies would be needed to find the active compounds behind these biological activities.

Rethinking Media Pluralism : A Critique of Theories and Policy Discourses

This study examines different ways in which the concept of media pluralism has been theorized and used in contemporary media policy debates. Access to a broad range of different political views and cultural expressions is often regarded as a self-evident value in both theoretical and political debates on media and democracy. Opinions on the meaning and nature of media pluralism as a theoretical, political or empirical concept, however, are many, and it can easily be adjusted to different political purposes. The study aims to analyse the ambiguities surrounding the concept of media pluralism in two ways: by deconstructing its normative roots from the perspective of democratic theory, and by examining its different uses, definitions and underlying rationalities in current European media policy debates. The first part of the study examines the values and assumptions behind the notion of media pluralism in the context of different theories of democracy and the public sphere. The second part then analyses and assesses the deployment of the concept in contemporary European policy debates on media ownership and public service media. Finally, the study critically evaluates various attempts to create empirical indicators for measuring media pluralism and discusses their normative implications and underlying rationalities. The analysis of contemporary policy debates indicates that the notion of media pluralism has been too readily reduced to an empty catchphrase or conflated with consumer choice and market competition. In this narrow technocratic logic, pluralism is often unreflectively associated with quantitative data in a way that leaves unexamined key questions about social and political values, democracy, and citizenship. The basic argument advanced in the study is that media pluralism needs to be rescued from its depoliticized uses and re-imagined more broadly as a normative value that refers to the distribution of communicative power in the public sphere. Instead of something that could simply be measured through the number of media outlets available, the study argues that media pluralism should be understood in terms of its ability to challenge inequalities in communicative power and create a more democratic public sphere.

Digital elevation model error in terrain analysis

Digital elevation models (DEMs) have been an important topic in geography and surveying sciences for decades due to their geomorphological importance as the reference surface for gravita-tion-driven material flow, as well as the wide range of uses and applications. When DEM is used in terrain analysis, for example in automatic drainage basin delineation, errors of the model collect in the analysis results. Investigation of this phenomenon is known as error propagation analysis, which has a direct influence on the decision-making process based on interpretations and applications of terrain analysis. Additionally, it may have an indirect influence on data acquisition and the DEM generation. The focus of the thesis was on the fine toposcale DEMs, which are typically represented in a 5-50m grid and used in the application scale 1:10 000-1:50 000. The thesis presents a three-step framework for investigating error propagation in DEM-based terrain analysis. The framework includes methods for visualising the morphological gross errors of DEMs, exploring the statistical and spatial characteristics of the DEM error, making analytical and simulation-based error propagation analysis and interpreting the error propagation analysis results. The DEM error model was built using geostatistical methods. The results show that appropriate and exhaustive reporting of various aspects of fine toposcale DEM error is a complex task. This is due to the high number of outliers in the error distribution and morphological gross errors, which are detectable with presented visualisation methods. In ad-dition, the use of global characterisation of DEM error is a gross generalisation of reality due to the small extent of the areas in which the decision of stationarity is not violated. This was shown using exhaustive high-quality reference DEM based on airborne laser scanning and local semivariogram analysis. The error propagation analysis revealed that, as expected, an increase in the DEM vertical error will increase the error in surface derivatives. However, contrary to expectations, the spatial au-tocorrelation of the model appears to have varying effects on the error propagation analysis depend-ing on the application. The use of a spatially uncorrelated DEM error model has been considered as a 'worst-case scenario', but this opinion is now challenged because none of the DEM derivatives investigated in the study had maximum variation with spatially uncorrelated random error. Sig-nificant performance improvement was achieved in simulation-based error propagation analysis by applying process convolution in generating realisations of the DEM error model. In addition, typology of uncertainty in drainage basin delineations is presented.

Monikasvoinen TAVA-partisiippi : Tutkimus suomen TAVA-partisiipin käyttökonteksteista ja verbiliittojen kieliopillistumisesta

The multifaceted passive present participle in Finnish This study investigates the uses of the passive present participle in Finnish. The participle occurs in a variety of syntactic environments and exhibits a rich polysemy. Former descriptions have treated it as a mainly modal element, but it has several non-modal uses as well. The present study provides an overview of its uses and meanings, with the main focus on the factors which trigger the modal reading. In addition, the study contains two case studies on modal periphrastic constructions consisting of the verb 'to be' and the present passive participle, the Obligation construction, e.g., on men-tä-vä [is go-pass-ptc], and the Possiblity construction, e.g., on pelaste-tta-v-i-ssa [is save-pass-ptc-pl-ine]. The study is based on empirical data of 9000 sentences obtained from i) large collections of transcribed material from Finnish dialects, ii) a corpus of modern Finnish newspaper texts, iii) corpora of Old Finnish texts. Both in colloquial and standard Finnish the reading of the participle is highly dependent of the context and determined by such factors as the overall syntactic environment and other co-occurring elements. One of the main findings here is that the Finnish passive present participle is not modal per se. The contextual modal reading arises whenever the state of affairs is conceptualized from the viewpoint of the implied subject of the participle, and the meaning of possibility or obligation depends mostly on whether the situation is pleasant or undesirable. In sections examining the grammaticalization of the Possibility and Obligation constructions, the perspective is diachronic. Both constructions have derived from copula constructions with the passive present participle as a predicate (adjective or adverb). These sections show how a linguistic change can be investigated on the basis of the patterns of usage in the empirical data. The Possibility construction is currently going through a restructuration to a passive verbal complex. The source of this construction is reflected in its present-day use by the fact that it heavily biased towards a small set of verbs. The Obligation construction has grammaticalized to a construction comparable to a compound tense. Patterns of use of the construction show that grammaticalization originates in specific syntactic constructions with an implication of practical necessity. Furthermore, it is shown that the Obligation construction has grammaticalized in different directions in standard and colloquial Finnish. Differing from the study on most typical phenomena investigated in the literature on grammaticalization of modality, the present study opens new perspectives and methods for discussion on these questions.