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  • 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.
1

ASSESSING EFFECTS TO ACQUATIC ORGANISMS OF CONTAMINANTS EXPOSURE ACROSS LEVELS OF BIOLOGICAL ORGANISATION, IN THE FRAME OF WFD 2000/60/EC

SACCHI, ANGELA 24 February 2011 (has links)
Gli ecosistemi acquatici sono il comparto ambientale finale per molti contaminanti introdotti nell’ambiente, specialmente per quelli persistenti, provenienti da diverse attività antropiche. Gli organismi acquatici sono esposti simultaneamente a differenti classi di composti chimici e, la loro fisiologia può esserne affetta anche da basse concentrazioni ambientali che ne determinano un effetto a cascata drammatico sull’intero ciclo vitale delle stesse. Per identificare gli effetti ecotossicologici si devono scegliere delle variabili di studio che sono sensibili a cambiamenti di esposizione e quindi possono registrare informazioni a differenti livelli di organizzazione biologica (ad es.: comunità, specie, alterazioni cellulari, molecolari). Il presente lavoro ha come scopo di studiare biomarker biochimici e bioindicatori su invertebrati acquatici capaci di rispondere all’effetto dei contaminanti e predirne il rischio di tossicità, requisito fondamentale dell’attuale legislazione comunitaria ambientale. Questo lavoro, nell’ambito della Water Frame Directive (WFD), affronta questa tematica con diversi tipi di approccio per implementare un sistema di monitorizzazione efficiente. Lo SPEAR ad esempio è in grado di diagnosticare la contaminazione di ecosistemi acquatici da pesticidi operando a livello di comunità di invertebrati acquatici. Inoltre si sono presi in considerazione anche biomarker a livello cellulare in bivalvi (Tapes philipphinarum and Mya arenaria): attività enzimatiche coinvolti nelle risposte aerobiche (CCO) e antiossidative (SOD and CAT), risposte genotossicologiche come la frequenza dei micronuclei, e, infine, a livello di organismo, risposte di carattere comportamentale. / Aquatic ecosystems are the final sink for most of contaminants introduced in the environment, especially persistent organic pollutants coming from different human activities. Most of the freshwater and coastal organisms are exposed simultaneously to different classes of chemicals, and their physiology may be affected by toxic chemical even at low environmental concentrations with a cascade event on population dynamics. Identifying ecotoxicological effects requires descriptors that are sensitive to changes in exposure and thus can indicate information at different levels of biological organisation (i.e. communities, sub-individual level). The present work aims to investigate biochemical biomarkers and bioindicators in aquatic invertebrates able to detect biological effects and predict risk of toxicity, with a special focus paid to the requirements of current EU regulation. Therefore, the present work faced on different kinds of approach identified to be efficient tools within the context of the WFD requirements (Water Frame Directive, 2000/60/EC), for investigative and operational monitoring. Work include the SPEAR approach as trait based indicator descriptor of freshwater aquatic macroinvertebrates communities, able to diagnose pesticide contamination in aquatic ecosystems. Further diagnostic approaches in environmental status are included, as assay representing biological responses for different enzymes involved in the aerobic (CCO) and antioxidant responses, (SOD, and CAT), behavioural endpoints, and genotoxicity biomarker associated with micronuclei frequency in bivalve species (Tapes philipphinarum and Mya arenaria).
2

Observation et modélisation spatiale de pratiques agricoles territorialisées à partir de données de télédétection : application au paysage bocager / Spatial observation and modeling of territorialized agricultural practices from remote sensing data : apply in bocage landscape

Vannier, Clémence 08 December 2011 (has links)
Aujourd’hui l’environnement connaît des bouleversements fondamentaux dus en grande partie à l’action de l’homme sur les milieux. En effet, tandis que les phénomènes climatiques et biophysiques ont été pendant longtemps les moteurs principaux des transformations des surfaces terrestres, l’Homme est aujourd’hui à l’origine de la majeure partie des transformations qui affectent les écosystèmes terrestres. Ainsi, les pratiques des acteurs du territoire jouent un rôle fondamental sur les modifications de l’usage des sols, et par conséquent sur les écosystèmes environnementaux. L’intensification de l’agriculture entraîne une dégradation des milieux « naturels », et de profonds changements dans les structures paysagères. Dans les régions bocagères, la gestion du réseau de haies joue un rôle déterminant dans la conservation des écosystèmes, de la biodiversité tant faunistique que floristique et également sur la qualité de l’eau, des sols, … Cette thèse, centrée sur les haies bocagères, porte plus particulièrement sur l’identification de pratiques agricoles territorialisées et sur leur organisation spatio‐temporelle. Les objectifs poursuivis dans cette thèse sont d’étudier les pratiques agricoles effectuées sur les haies en Bretagne à travers leurs interactions avec les structures paysagères, et d’en modéliser le fonctionnement, afin de comprendre comment elles influencent la dynamique du paysage.L‘identification et la caractérisation des pratiques agricoles ont été effectuées à partir de l’évaluation de différents types d’images de télédétection à haute et très haute résolution spatiale et de données laser aéroportées LiDAR, en utilisant une approche de classification contextuelle orientée‐objets. La modélisation des pratiques agricoles a été réalisée avec un modèle multi‐agents, afin de prendre en compte la dimension spatiale des jeux d’acteurs pour évaluer l’influence des pratiques agricoles sur l’évolution du réseau de haies. Les résultats de l’observation du réseau bocager à partir des données de télédétection mettent en avant leur complémentarité : la caractérisation de la continuité des haies à un niveau fin est rendue possible grâce aux images à très haute résolution spatiale, tandis que la détermination et la cartographie des pratiques agricoles à l’échelle de l’arbre peut être appréhendée à partir de données laser aéroportées de type LiDAR. L’observation et la caractérisation du réseau de haies ont permis de déterminer l’arrangement spatial des structures boisées en prenant en compte non plus seulement la présence des éléments mais également leur emprise dans le paysage et leur agencement au sein de la dynamique temporelle des successions culturales. Le modèle multi‐agents développé a permis d’analyser l’influence des pratiques agricoles sur la dynamique du paysage, et de déterminer l’importance de décisions prises au niveau local sur l’évolution du réseau de haies à une échelle supérieure / Today the environment is experiencing fundamental changes, largely due to human activity. Indeed, while climate and biophysical phenomena have been the main drivers of land surface transformations for a long time, humans are now responsible for most of the changes affecting terrestrial ecosystems. Thus, the practices of local actors play a key role in land use change and therefore in environmental ecosystems. Intensification of agriculture causes degradation in the “natural” environment and significant changes in landscape structures. In “bocage” regions, hedgerow network management plays a key role in ecosystem conservation, biodiversity, vegetation and wildlife and in the quality of water, soil, etc. This thesis focuses on hedgerows, and especially on the identification of territorialized agricultural practices and their space‐time organization. The objectives of this thesis are to study hedgerow agricultural practices in Brittany through their interactions with landscape structures, and to model their organization, in order to understand how they influence landscape dynamics. The process of identification and characterization of agricultural practices was undertaken by evaluating different types of remote sensing images with high and very high spatial resolution and airborne LiDAR data, using a contextual approach to object‐oriented classification. The modeling of agricultural practices was performed with a multi‐agent model in order to take into account the spatial dimension of actor decisions and to evaluate the influence of agricultural practices on hedgerow network evolution. The results of the hedgerow network analysis using remote sensing data highlight their complementarities: detailed characterization of hedgerow continuity is made possible using high spatial resolution images, while determination and mapping of agricultural practices at the tree scale can be seen from airborne LiDAR data. The process of observation and characterization of the hedgerow network allows determination of the spatial arrangement of the woody structure, by taking into account not only the presence of individual elements, but also their extent in the landscape and their spatial arrangement within crop succession temporal dynamics. The multi‐agent model developed allowed analysis of the influence of agricultural practices on landscape dynamics, and determination of the importance of making local level decisions on the hedgerow network evolution at a larger scale
3

Fysiologiska processer vid medicinsk abort : samt didaktisk tillämpning i högstadie- och gymnasieskolans biologiundervisning / Physiological processes in medical abortion : and didactical application in secondary and upper secondary school biology teaching

Julsgård, Sara, Kilborn, Josefine January 2021 (has links)
De två läkemedel som administreras vid medicinsk abort i Sverige idag består av de aktiva substanserna mifepriston respektive misoprostol. Behandlingskuren bygger på effekter hos de endogena ämnena progesteron och prostaglandiner. I denna studie beskrivs fysiologiska processer under graviditeten med avseende på progesteron och prostaglandiner samt vid medicinsk abort med avseende på mifepriston och misoprostol. Valet av fokus på fysiologiska processer speglar biologilärarens didaktiska uppgift i att undervisa om hur människokroppen fungerar och dess interaktion med läkemedel. Slutligen presenteras och diskuteras även möjligheter och svårigheter med undervisning om abort inom ramen för högstadie- och gymnasieskolans biologiundervisning. / The drugs administrated to cause medical abortion consist of one tablet with the active substance mifepristone and one with the active substance misoprostol. The regime is based on effects of the endogenic substances progesterone and prostaglandins. In this study, physiological processes in pregnancy regarding progesterone and prostaglandins are described, as well as the physiological processes in medical abortion with respect to mifepristone and misoprostol. The focus on physiological processes relates to the mission of the biology teacher to explain how the human body works and interacts with medical drugs. Finally, opportunities and difficulties with instructions on abortion in secondary and upper secondary school biology are presented and discussed.
4

Students’ meaning-making of epigenetic visual representations : An exploration within and between levels of biological organization

Thyberg, Annika January 2024 (has links)
This thesis explores lower secondary students’ meaning-making of epigenetic visual representations within and between biological organization levels. Data obtained from five focus group discussions where students indicated and reasoned about eight epigenetic visual representations were explored. By analyzing students’ interactions with multiple visual representations, and the impact of linking and reasoning patterns on their meaning-making, the research contributes insights to the learning of epigenetics.  Epigenetics, which is gaining rapid importance in emerging biology curricula, is communicated at different biological organization levels, and serves as the meaning-making context explored in the thesis. A compelling biology didactics context, where students are required to reason with multiple representations depicted within and between organizational levels to make meaning about epigenetics. The thesis uncovers three primary findings. First, four linking patterns in students’ meaning-making across and between organizational levels using various visual representations are illuminated. Second, five visual characteristics that influence students’ linking within and between levels were discerned. Third, students’ meaning-making processes were observed to emerge through four phases, which involved form and function attributes of the visual representations, and the transfer of scientific ideas across representations. / <p>Article 1 published in thesis as manuscript, now published.</p>

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