• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 219
  • 62
  • 12
  • 9
  • 4
  • 4
  • 3
  • 1
  • 1
  • Tagged with
  • 316
  • 316
  • 54
  • 51
  • 51
  • 49
  • 42
  • 42
  • 35
  • 33
  • 28
  • 23
  • 21
  • 21
  • 21
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

L'apport de l'imagerie satellitale à la surveillance maritime. Contribution géographique et géopolitique / Non communiqué

Fournier, Mélanie 10 December 2012 (has links)
Que l’on se situe dans les Caraïbes, en mer Baltique ou en mer Méditerranée, bassins à la fois stratégiques, fragiles et inégaux, il reste crucial pour les Etats riverains d’y établir une surveillance des activités légales et illégales. Nous avons sélectionné ces bassins maritimes comme terrain d’analyse de notre recherche qui repose sur l’étude des grands projets européens dédiés à la surveillance maritime. Ce travail vise d’abord à proposer un état de l’art : il cherche à établir une synthèse des services proposés par les grands industriels travaillant sur les marchés civils et militaires et à évaluer dans quelle mesure il serait possible d’améliorer et de compléter les technologies existantes. Il a aussi pour objectif d’évaluer les informations recueillies via une image satellitale par l’établissement d’un historique des outils d’observation utilisés pour la surveillance maritime avec leurs caractéristiques, leurs avantages et inconvénients. / The Caribbean Sea, the Baltic Sea and the Mediterranean Sea are some of the most strategic maritime basins. In such sensitive, unequal and sometimes unstable regions, it is necessary for the coastal states to develop and/or enhance their maritime surveillance. We chose these regions as the center for our analysis. The research is based on the latest European maritime projects. First of all this study aims at creating a state of the art. The objective is to make a synthesis of the services provided by industries in both military and civil fields. We would like to estimate how it would be possible to improve and to complement the existing technologies. Secondly the aim is to estimate the value of the information and data extracted from a satellite image. We will answer this question by creating an historical account of observation tools used for maritime surveillance with their characteristics, advantages and drawbacks.
202

Learning ecosystem complexity : A study on small-scale fishers’ ecological knowledge generation

Garavito-Bermúdez, Diana January 2016 (has links)
Small-scale fisheries are learning contexts of importance for generating, transferring, and updating ecological knowledge of natural environments through everyday work practices. The rich knowledge fishers have of local ecosystems is the result of the intimate relationship fishing communities have had with their natural environments across generations (see e.g. Urquhart and Acott 2013). This relationship develops strong emotional bonds to the physical and social place. For fishing communities and fishers – who depend directly on local ecosystems to maintain their livelihoods – fishing environments are natural places for living, working and defining themselves. Previous research on fishers’ ecological knowledge has mainly been descriptive, i.e., has focused on aspects such as reproduction, nutrition and spatial-temporal distribution and population dynamics, from a traditional view of knowledge that only recognises scientific knowledge as the true knowledge. By doing this, fishers’ ecological knowledge has been investigated separately from the learning contexts in which it is generated, ignoring the influence of social, cultural and historical aspects that characterise fishing communities, and the complex relationships between fishers and the natural environments they live and work in. This thesis investigates ecological knowledge among small-scale fishers living and working in the ecosystems of Lake Vättern and the Blekinge Archipelago (Baltic Sea) in Sweden and explores how ecological knowledge is generated with particular regard to the influences of work and nature on fishers’ knowledge of ecosystems. The aim of this thesis is to contribute to the knowledge and understanding of informal learning processes of ecosystem complexity among small-scale fishers. This knowledge further contributes to the research field of ecological knowledge and sustainable use and management of natural resources. It addresses the particular research questions of what ecological knowledge fishers generate, and how its generation is influenced by their fishing work practices and relationships to nature. The thesis consists of three articles. Article I focuses on the need to address the significant lack of theoretical and methodological frameworks for the investigation of the cognitive aspects involved in the generation of ecological knowledge. Article II deals with the need to develop theoretical, methodological and empirical frameworks that avoid romanticising and idealising users’ ecological knowledge in local (LEK), indigenous (IEK) and traditional (TEK) ecological knowledge research, by rethinking it as being generated through work practices. Article III addresses the lack of studies that explicitly explore theories linking complex relations and knowledge that humans form within and of ecosystems. It also addressed the lack of attention from environmental education researchers to theory and empirical studies of ‘sense of place’ research, with a particular focus on environmental learning. Research into the question of what ecological knowledge fishers generate shows differences in their ways of knowing ecosystem complexity. These differences are explained in terms of the influences of the species being fished, and the sociocultural contexts distinguishing fishers’ connection to the fishing profession (i.e., familial tradition or entrepreneurship) (Article I), but also by the fishing strategies used (Article II). Results answering the research question of how work practices influence fishers’ knowledge of ecosystem complexity show a way of rethinking their ecological knowledge as generated in a continuous process of work (Article II), thus, far from romantic views of knowledge. Results answering the research question of how fishers’ relationships to nature influence their knowledge of ecosystem complexity demonstrate the complex interconnections between psychological processes such as identity construction, proximity maintenance and attachment to natural environments (Article III). Finally, more similarities than differences between fishers’ knowledge were found, despite the variation in cases chosen, with regards to landscape, target species, regulations systems and management strategies, fishing environments scales, as well as cultural and social contexts. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 2: Manuscript.</p><p> </p> / Ecological knowledge and sustainable resource management: The role of knowledge acquisition in enhancing the adaptive capacity of co-management arrangements
203

Flytande biogas som bränsle för sjöfartssektorn : Möjligheter och hinder för Östersjöområdet / Liquid biogas as a fuel for shipping : Possibilities and challenges in the Baltic Sea

Lindskog, Henrik January 2019 (has links)
Syftet med denna uppsats är att bidra till en bättre förståelse för LBG:s förutsättningar inom sjöfarten genom att kartlägga vilka möjligheter och hinder som finns för att använda LBG som bränsle i Östersjöområdet. Studien består av en analytisk kartläggning som baseras i en litteraturstudie och kompletteras av en intervjustudie med branschaktörer.  Uppsatsen använder en kombinerad PESTLE/SWOT-metodik, där en kartläggning har utförts med hjälp av en PESTLE-analys för att identifiera områden och faktorer. Faktorerna har därefter analyserats genom en SWOT-analys för att svara på rapportens formulerade huvudfrågeställning. Resultatet visar att potentialen för LBG inom sjöfartsbranschen är stor, särskilt då den huvudsakliga infrastrukturen för bränslet finns på plats med anledning av LNG:s framväxt i Östersjöområdet. Den volymmässiga avsättningspotentialen för bränslen är också stor inom sjöfarten, och LBG har unika styrkor jämfört med LNG och i sjöfarten redan etablerade bränslen. LBG:s styrkor ligger i linje med de målsättningar som finns kring omställning till förnybara bränslen i transportsektorn, samt de strategier och mål som finns om att reducera koldioxidutsläpp på global och europeisk nivå. Intervjuade rederier menar att de ser utvecklingen mot LBG som ett naturligt steg för sin LNG-drivna flotta och att testverksamhet pågår med inblandning av LBG i LNG-drivna fartyg. Tre faktorer identifierades som särskilda viktiga för utvecklingen mot LBG i sjöfartsbranschen i Östersjön. En av dessa berör produktionskapaciteten av LBG, där sjöfartsbranschens stora energibehov medför att endast en begränsad inblandning av LBG är möjlig i dagsläget. Ett annat identifierat fokusområde består i LBG-kostnad för sjöfarten, där den hårda konkurrenssituationen inom branschen negativt påverkar rederiers möjligheter att bekosta inblandning av LBG. Förutsättningarna påverkas också av att fartygsbränslen för kommersiell sjöfart är skattefria och att andra potentiella branscher för LBG medger möjlighet till skattemässiga subventioner. I uppsatsen skissas det på förslag för hur man kan avhjälpa dessa hinder och bättre utnyttja LBG:s styrkor som fartygsbränsle i Östersjöområdet. / The purpose of this paper is to contribute to a better understanding of LBG's conditions in the shipping sector by mapping out the opportunities and barriers of using LBG as fuel in the Baltic Sea area. The paper consists of a literature study that is supplemented by an interview study with industry players. The thesis uses a combined PESTLE / SWOT methodology, where a survey has been performed using a PESTLE analysis to identify areas and specific factors. The factors were then analyzed through a SWOT analysis to answer the main issue proposed by the author. The results show that there is considerable potential for LBG in the shipping industry, especially as the entire fuel infrastructure is in place due to LNG's continuous growth in the Baltic Sea area. LBG has unique strengths compared to both LNG and fuels that are already established in the maritime industry. LBG's strengths are in line with the aims of increasing renewable fuels in the transport sector, as well as the strategies and targets that exist to reduce carbon dioxide emissions at a global and European level. Interviewed shipping companies see the development towards LBG as a natural step for their LNG-operated fleet, and that testing is ongoing with mixing LBG in some LNG-fueled vessels. Three factors were identified as particularly important for the development of LBG in the Baltic Sea. One of these concerns the production capacity of LBG, where the large energy needs of the shipping industry mean that only a limited use of LBG is possible at present. Another identified focus area is costs in relation to LBG, where the tough competitive situation in the shipping industry negatively impacts shipping companies' ability to afford a more expensive fuel like LBG. The prerequisites are also affected by the fact that ship fuels for commercial shipping are tax-free and that other potential sectors for LBG allow for tax subsidies. The thesis outlines proposals for how to overcome these obstacles and make better use of LBG's strengths as a fuel for shipping in the Baltic Sea area.
204

La mer Baltique comme destination de voyages : l'espace baltique à travers les récits de voyages français et allemands (1750-1815) / Reiseziel mare Balticum : Der ostseeraum im spiegel deutscher und französischer reisebeschreibungen (1750-1815)

Manske, Maike 19 December 2013 (has links)
Dans les récits de voyages des années 1800, la région de la mer Baltique est présentée commeun espace de découverte diversifié – c’est en quelque sorte un patchwork multicolore deconstructions imagologiques. Pourtant, la conception d’une région de la mer Baltique étaitdéjà fondée à l’époque de la «Sattelzeit» sur le besoin de pouvoir situer les riverains de la merBaltique comme une unité culturelle, quelque part dans le grand Nord. Dans l’imaginationdes voyageurs en 1800, la région de la mer Baltique est en fait déjà cet espace d’interactionset d’imbrications qui constitue la base évidente des approches modernes de la recherche.Bien sûr, il y avait les divers royaumes, provinces ou villes qui jouèrent un rôle pour lesvoyageurs. Cela ne signifie pourtant pas qu’il soit impossible de retrouver dans les récits devoyages certains points communs, manifestés sous forme d’un caractère «nordique»supérieur de ces riverains. C’est pourquoi ce caractère «nordique» est sans cesse exprimédans les récits de voyages à partir de divers niveaux de perception – dans la description de lanature, de la mer, du climat, mais aussi dans les perceptions des villes et les rencontresculturelles. Par conséquent, la littérature de voyage indique une tendance qui est égalementimportant pour la recherche historique actuelle: une évaluation de la région de la merBaltique comme un macro-région unique, qui accepte aussi les différences dans leursdifférents pays et régions. / This Franco-German analysis examines the Baltic Sea region as a center for cultural exchangebased on German and French travel reports from 1750 to 1815 in a comparative perspective.The objective is to examine the countries around the Baltic Sea as places of encounter fortravelers and to raise the awareness of historical travel research and research of culturalexchange for the subject ‘space’. This approach scrutinizes several forms of German andFrench imaginations of nature, sea shore and different forms of urbanity, but also theperception and reception of identities and alterities, the consolidation and the departure ofstereotypes as well as the possibilities and limits of cultural transfer processes by travelling.Furthermore, this approach allows to gain a deeper understanding of the progress of complexphenomena such as, ‘percipience', 'contemplation' and 'delineating' of foreign cultures in aperiod which was marked by a radical change in socio-political and cultural thinking.
205

Storm Frequency in the Northern Baltic Sea Region and its Association to the North Atlantic Oscillation

Arra, Venni January 2018 (has links)
Storms can be both destructive and valuable at the same time. They expose coastal areas to various risks but can also enhance the supply of wind energy and provide marine ecosystems with oxygen rich water. As the North Atlantic Oscillation (NAO) is known to have a significant impact on the wind climate in Europe, investigating its interconnection to storm frequency and intensity under global warming circumstances in the Northern Baltic Sea region was of interest in this study. Wind speed data series of annual storm counts were obtained from five meteorological stations along with PC-based NAO values over the period 1960-2017. The data series were analysed in Microsoft Excel and modelled using a Poisson regression or negative binomial regression model in SPSS Statistics. The results display an unsystematic spatial pattern both in the association to the NAO as well as in the overall storm frequency. However, storm (≥ 21 m s-1) frequency has generally been decreasing, whereas the proportion of severe storms (≥ 24 m s-1) has slightly been increasing, suggesting a tendency toward stronger but fewer storms. Even though only certain data series display statistically significant findings (p ≤ .05), a majority of the winter storms and severe winter storms display a positive association, indicating that a higher NAOI is related to a greater number of winter storms. The spatial and temporal variability in the obtained results can partially be explained by storm tracks and prevalent wind directions. Nevertheless, inhomogeneities do presumably affect the wind speed observations through internal and external influences and changes related to the meteorological stations. Future research should, therefore, also consider integrating other storm related parameters, such as direct air pressure measurements, wave heights and storm surges, as well as implement different data homogenization methods and techniques.
206

Making water information relevant on local to global scale – the role of Information Systems for Integrated Water Management

Hannerz, Fredrik January 2008 (has links)
<p>Relevant information is essential for finding solutions in Integrated Water Management (IWM). Complex water systems and a need for increasing integration of sectors, actors and scales in IWM require new methods for developing and managing such information. This thesis investigates the role of information within the IWM process, as well as the main challenges for development of representative, accessibleand harmonized information. Results show how information needs and the information production process for IWM may be systematized, and indicate a large potential for information system development for IWM. However, in order to reach the full potential, today’s limited and heterogeneous water information needs to become more comprehensive, transparent, interoperable, dynamic, scalable and openly accessible. Large pressures on water systems are found in coastal catchment areas that are unmonitored across the local to the global scale, indicating a large importance of these areas for nutrient and pollutant loading. The globally accessible runoff data from catchment areas that are rich in pressures from population, agriculture and general economic activity further exhibit a rapidly declining trend during recent years. Major water system changes may therefore pass unnoticed if analyzed on the basis of openly accessible runoff global data. Furthermore, large discrepancies are found between land cover databases, which may result in major uncertainties in quantification of water and evapotranspiration flows. Identified information challenges may be relatively easily overcome by making better use of available information, while other challenges such as development of consistent baselines of core data and a possible re-prioritization of water-environmental monitoring programs may be both difficult and costly.</p>
207

Mechanisms structuring the pelagic microbial food web : Importance of resource and predation

Samuelsson, Kristina January 2003 (has links)
<p>Temporal and spatial variations of pelagic microorganisms in the northern Baltic Sea were studied, as well as factors influencing their abundance and growth rates. Three main questions were asked 1) How does increased productivity influence the structure of the microbial food web? 2) Does predation limitation vary between trophic levels? 3) What is the relative importance of resource and predation limitation at different trophic levels?</p><p>A field study in the northern Baltic Sea showed that dominating protozoa, flagellates and ciliates, increased with increasing primary productivity from north to south. Furthermore, relatively small protozoan cells dominated in the low productive north, while larger cells became more dominant in the south. The relationship between plankton size structure and productivity was further studied in an experimental system. In agreement with present theories regarding nutrient status of pelagic food webs, increased productivity caused a lengthening of the food chain as well as a change in plankton size structure. While microplankton dominated in nutrient rich treatments pico- and nanoplankton dominated during nutrient poor treament. The flagellate community was dominated by a potentially mixotroph, <i>Chrysochromulina</i> sp., at low nutrient concentrations. To our knowledge this is the first experimental study showing that <i>Chrysochromulina</i> sp. in resemblance with other mixotrophs is favoured by nutrient poor conditions compared to strict autotrophs and heterotrophs.</p><p>During a stratified summer period autotrophic microorganisms in the northern Baltic Sea did not respond to removal of potential predators, indicating that they were primarily limited by inorganic nutrients. An exception was small eucaryotic picoplankton that showed a large response to predator removal. Among the heterotrophic microorganisms direct effect of predation seemed to increase from ciliates, heterotrophic bacteria, small heterotrophic flagellates, medium flagellates to large flagellates. No quick indirect effect was observed, but after four days trophic cascades were detected.</p><p>The relative importance of resource and predation limitation was studied among heterotrophic bacteria, flagellates and ciliates in the northern Baltic Sea. For all these groups, resource limitation seemed to prevail during the summer period. The results also indicated that the relative importance of predation increased with the productivity of the system. To our knowledge there are no earlier measurements on the relative importance of resource and predation limitation for micoorganisms in the pelagic environment.</p>
208

How to ensure that the nightmare won’t happen again : Bankernas nyckeltal, kapitalstruktur och riskreglering i ett konjunkturperspektiv

Johansson, Gustav, Söderlund, Fredrik January 2009 (has links)
<p>Syftet är att evaluera Baselramverkets riskreglering i en konjunkturcykel med hänsyn till Östersjöregionens storbankers systemviktiga funktion.</p><p>Studien antar främst en kvantitativ ansats i de två första delarna, nyckeltalsanalysen och buffertsimuleringen men även en kvalitativ ansats antas i den tredje delen, intervjuer.<strong> </strong></p><p>Studien utgår från teorierna om Basel I och Basel II, nyckeltalsteori samt från tidigare forskning.</p><p>Resultatet i studien består av nyckeltalanalys och simulering av åtta, i Östersjöregionen verksamma, bankers nyckeltal och buffert under 21 år samt sex djupintervjuer med representanter för såväl banker som regulatorer.</p><p><strong> </strong><strong>Slutsatser</strong></p><p>Att det inte finns något samband mellan Baselregleringens kapitaltäckning och bankernas risk eller konjunktur, att riskvägningen tenderar till att vara godtycklig och har större påverkan på buffert än Baselregleringens kapitaltäckning samt att mer transparens behövs i bankerna tyder på att Baselregleringens kapitaltäckningskrav i mycket liten utsträckning visar Östersjöregionens storbankers faktiska risk.</p> / <p>The purpose is to evaluate the Basel framework risk regulation in an economic cycle, in account to the systemic function of the large banks in the Baltic Sea region.</p><p>The study mainly adopts a quantitative approach in the two first parts, the key ratio analysis and the buffer simulation. A qualitative element is also implemented in the third part, interviews.</p><p>In a theoretical perspective the study is based on the Basel I and Basel II framework, key ratio theories and previously conducted research. </p><p>The result<strong> </strong>consists of key ratios analysis and buffer simulation for eight banks in the Baltic Sea region for a period of 21 years and interviews with six representatives of banks and regulatory institutions.</p><p> <strong>Conclusion                                   </strong></p><p>The absence of correlation between the Basel regulation capital adequacy and the bank risk nor economic cycle, that risk weighting tends to be arbitrary and have greater impact on bank buffer than capital adequacy regulation has, and that more transparency is needed in banking; suggests that the Basel capital adequacy to a small extent reflect actual risk.</p>
209

Macroalgae in the Baltic Sea : responses to low salinity and nutrient enrichment in Ceramium and Fucus

Bergström, Lena January 2005 (has links)
<p>The brackish Baltic Sea is a marginal environment for both marine and freshwater species. The rate of ecological differentiation is presumably high due to strong selection pressure from a gradient of decreasing salinity that has been present in its current state for only about 3 000 years. Even more recently, increased nutrient loading due to human activities has affected the growth rate of species, with potential effects on their competitive interactions and responses to other regulating factors. I have investigated the potential effects of low salinity and nutrient enrichment on the distributional ranges of two marine macroalgae with a wide distribution in the Baltic Sea, the red alga <i>Ceramium tenuicorne</i> (Kütz.) Wærn and the brown alga <i>Fucus vesiculosus</i> L. </p><p>A field study in the northern Baltic Sea indicated a strong relationship between the community structure of macroalgae and abiotic factors even on a small, local scale. The abiotic factors are potentially modulated by eutrophication, which may have a strong effect on the depth distribution and abundance of macroalgae. On a regional scale, laboratory experiments suggested that nutrient enrichment is unlikely to affect the distribution of <i>Ceramium</i> and <i>Fucus</i> along the salinity gradient. Growth in <i>Ceramium</i> from the Baltic Proper was enhanced by nitrate and phosphate, but the response did not override growth constraints due to low salinity. <i>Ceramium</i> from the Gulf of Bothnia had an inherently lower growth rate that was not positively affected by nitrate and phosphate increase. In <i>Fucus vesiculosus</i>, reproductive performance was impaired by nitrate and phosphate levels corresponding to ambient levels in eutrophicated areas of the Baltic Sea, when measured by their effect on zygote attachment, germination, and rhizoid development.</p><p>The wide distribution of <i>Ceramium</i> in the inner Baltic Sea is probably related to local adaptation, rather than a generalized tolerance of different salinity levels. Ecotypic differences were observed when comparing strains from the Baltic Proper (salinity 7 psu) and the Gulf of Bothnia (4 psu). A high rate of vegetative reproduction was evident, although sexual reproduction was occasionally observed in salinity 4. In <i>Fucus vesiculosus</i>, genetic and morphological analyses of sympatric and allopatric populations of the common, vesicular, morphotype and a dwarf morphotype, characteristic for the Gulf of Bothnia, showed that the dwarf morphotype represents a separate evolutionary lineage. Also, vegetative reproduction was observed in <i>Fucus</i> for the first time, as supported by genetic and experimental data. </p><p>The results show that the biota of the inner Baltic Sea may have unique adaptive and genetic properties, and that it is highly relevant to consider subspecies diversity in Baltic Sea management.</p>
210

Pelagic microorganisms in the northern Baltic Sea : Ecology, diversity and food web dynamics

Berglund, Johnny January 2005 (has links)
<p>Heterotrophic microorganisms are important for the flow of carbon and nutrients in the sea. Bacteria, nanoflagellates and ciliates are relevant components of the pelagic food web. In order to be able to predict the outcome of e.g. eutrophication or climate change we need to know how the different components of the pelagic food web are regulated. With the focus on the northern Baltic Sea food web, this thesis deals with limitation and control of heterotrophic protists, the effect of resource heterogeneity on food web efficiency and diversity of nanoflagellates.</p><p>In-situ microcosm experiments showed that the net growth of heterotrophic flagellates were resource limited throughout the year. Field data confirmed that the abundance of flagellates was bottom-up controlled. Furthermore, field data also showed that the annual average biomass of protists, flagellates and ciliates increased with primary productivity. On a smaller seasonal scale temperature and bacterial biomass were able to explain most of the variation in flagellate biovolume. The temporal variation in ciliate biovolume could not be explained by any bottom-up factors like bacterial biomass, flagellate biomass or chlorophyll a. This and an in-situ microcosm experiment implied that the seasonal dynamics of ciliates were more regulated by predators like mesozooplankton.</p><p>The food web efficiency i.e. how much of production at the resource level is converted to production at the top trophic level, may be affected by specific size or type of resource. Indoor mesocosms revealed that the food web efficiency was 11 times lower when heterotrophic bacteria dominated basal production instead of nano- and micro-sized phytoplankton. This was due to a lengthening of the food web when pico-sized bacteria constituted the main resource.</p><p>The PCR-DGGE molecular biological method was used to study the diversity of heterotrophic or mixotrophic chrysomonads. The focus was set on chrysomonads due to their relatively large contribution to the nanoflagellate community. Group-specific PCR primers were optimized for the target group. A field survey in the northern Baltic Sea showed that a handful of chrysomonad sequences were present throughout the year. Significantly more chrysomonads were recorded in the basin with higher primary productive and salinity. In total 15-16 different chrysomonad sequences were recorded. Most of them matched uncultured chrysomonad clones.</p>

Page generated in 0.0648 seconds