Dissertations / Theses on the topic 'Geopolitical and global changes'

The flux of carbon in to and out of the atmosphere exerts a fundamental control over the Earth's climate. The oceans contain almost two orders of magnitude more carbon than the atmosphere, and consequently, small fluctuations within the oceanic carbon reservoir can have very significant effects on air-sea CO₂ exchange, and the climate of the planet. Pelagic carbonates represent a major long-term flux of carbon from the surface ocean to deep-sea sediments. Within sediments, the biologically produced carbonates act as a longterm carbon store, but also as chemical recorders of past surface ocean conditions. Counterintuitively, despite the production and sedimentation of carbonate acting as a CO₂ sink, over periods shorter than the mixing-time of the ocean, the pH change associated with calcium carbonate precipitation enriches the surface waters in CO₂ and elevates the equilibrium value of gaseous exchange with the atmosphere. Coccolithophores, ubiquitous marine photosynthetic plankton, produce calcium carbonate plates, coccoliths, which account for around one third of all marine calcium carbonate production. Sedimentary coccoliths therefore represent a valuable repository of surface ocean geochemical data, as well as a very significant carbon-cycle flux. This thesis examines how the mass of calcium carbonate produced by coccolithophores has changed in response to rising levels of atmospheric CO₂. A -40% increase in average coccolith mass over the last 230 years, paralleling anthropogenic CO₂ release, is demonstrated within a high-accumulation rate North Atlantic sediment core. Additionally, a flow-cytometry method is presented, which enables the automatic separation of coccoliths from clay particles in sedimentary samples, representing the first step in a coccolith cleaning procedure, which should ultimately enable down-core measurements of coccolith trace-element/calcium ratios. Complementing this work I describe results from continuous dissolution analysis of cultured coccoliths which allows a first-order evaluation of trace-element partitioning into coccoliths produced by the species Coccoliths pelagicus, and present a conceptual methodology to allow the determination of single-species coccolith chemical data.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1990.<br>Archives copy lacks leaf 247.<br>15 folded maps in pocket.<br>Includes bibliographical references (leaves 120-140).<br>by José Wilson Corrêa Rosa.<br>Ph.D.

How can we model global phenomenon based on local interactions? Agent-Based (AB) models are local rule-based discrete method that can be used to simulate complex interactions of many agents. Unfortunately, the relative ease of implementing the computational model is often counter-balanced by the difficulty of performing rigorous analysis to determine emergent behaviors. Calculating existence of fixed points and their stability is not tractable from an analytical perspective and can become computationally expensive, involving potentially millions of simulations. To construct meaningful analysis, we need to create a framework to approximate the emergent, global behavior. Our research has been devoted to developing a framework for approximating AB models that move via random walks and undergo state transitions. First, we developed a general method to estimate the density of agents in each state for AB models whose state transitions are caused by neighborhood interactions between agents. Second, we extended previous random walk models of instantaneous state changes by adding a cumulative memory effect. In this way, our research seeks to answer how memory properties can also be incorporated into continuum models, especially when the memory properties effect state changes on the agents. The state transitions in this type of AB model is primarily from the agents’ interaction with their environment. These modeling frameworks will be generally applicable to many areas and can be easily extended.

Thesis (MA)--Stellenbosch University, 2011.<br>ENGLISH ABSTRACT: The 2008 global economic crisis marks the beginning of considerable systemic changes in global governance. The ‘Group of 20’ (G20), which entered the centre stage of global governance in response to the crisis, may be seen as both a result of and as a vehicle for those changes. Representing some 85 per cent of the global economy the group has the potential to alter the international order almost by stealth. Hence, there is good reason for undertaking a deeper examination of its role in and impact on global governance. This study critically examines some of the changes in global governance embodied – and brought about – by the G20. By using analytical tools from the critical theory of Robert Cox and constructivism, it studies changes in three dimensions of global governance: the material, the institutional and the ideational, so as to achieve a holistic understanding of the nature of the changes taking place within global governance. In so doing, the study sheds light on the role of the G20 in global governance, the impact of the group on global cooperation and the nature of the shift in global governance that it represents.<br>AFRIKAANSE OPSOMMING: Die 2008 globale ekonomiese krisis kan as die begin van aansienlike sistemiese veranderinge in globale regeerkunde beskou word. Die 'Groep van 20' (G20), wat in reaksie op die krisis ’n sentrale rol in globale regeerkunde ingeneem het, kan as beide 'n resultaat en drywer van hierdie veranderinge gesien word. Die groep verteenwoordig ongeveer 85 persent van die globale ekonomie, en het dus die potensiaal om grootskaalse verandering in die internasionale orde te weeg te bring. Dit is dus belangrik om die groep se rol in globale regeerkunde meer deeglik te ondersoek. Deur gebruik te maak van analitiese metodes wat gebasseer is op die kritiese teorie van Robert Cox asook konstruktivisme, ondersoek hierdie studie veranderinge in drie dimensies van globale regeerkunde. Materiële en institusionele veranderinge, asook veranderinge binne die dimensie van idees, word geïdentifiseer met die oog op 'n meer holistiese begrip van die aard van die veranderinge. Die studie werp daardeur lig op die rol van die G20 in globale regeerkunde, die groep se impak op globale samewerking, en die aard van die magsverskuiwing in globale regeerkunde wat dit verteenwoordig.

Observations suggest that properties of Antarctic Intermediate Water (AAIW) are changing. The impact of these variations is explored using a series of idealised perturbation experiments. Two sets of ensembles have been used. The first varied initial atmospheric states; the second varied initial states in the ocean and atmosphere. The ensemble simulations were integrated over 120 and 100 years, respectively, altering AAIW from 10-200S in the Atlantic, Pacific and Indian oceans separately in a coupled climate model, HadCM3. Potential temperature was changed by ±1 DC, along with corresponding changes in salinity, maintaining constant potential density. There is a surface response to changes in AAIW in each of the three major ocean basins. When the water mass surfaces in the equatorial regions, there is no significant change in sea surface temperature (SST). However, there is a SST response when the anomalies surface at higher latitudes (>300). Anomalous sea-to-air heat fluxes leave density anomalies in the ocean. Resulting changes in ocean circulation cause responses to opposite perturbations to be nonlinear. In the Southern Ocean, changes in the meridional density gradient lead to changes in Antarctic Circumpolar Current transport. The North Atlantic is particularly sensitive, with density anomalies causing changes in the meridional overturning circulation of up to 1 Sv. Surfacing anomalies and changes in meridional ocean heat transport cause basin-wide changes in the surface ocean and overlying atmosphere on multi-decadal timescales. Cooling in the North Atlantic Current may be self-sustaining as it leads to high pressure anomalies in the overlying atmosphere, and increased wind stress over the sub-polar gyre. The spatial pattern of SST anomalies in the North Pacific resembles the Pacific Decadal Oscillation. Heat and salt distribution in the Indian Ocean is influenced by the Indonesian Through-Flow (ITF). Long-term trends in the ITF are caused by bottom pressure anomalies in the Pacific.

Thesis (DPhil)--Stellenbosch University, 2015.<br>ENGLISH ABSTRACT: This study is informed by both the deficit/positivist and contextual/critical models for doing public understanding of science (PUS) research and seeks to investigate factors that influence the perceptions, beliefs and attitudes towards climate change in Malawi. Previous research on the public understanding of climate change conducted in the United States of America (USA) and Europe suggest that people‘s beliefs, perceptions and attitudes do influence support for both voluntary and policy initiatives to address climate change and adaption to it. However, it is equally important to understand the factors that influence public perceptions, beliefs and attitudes towards climate change. An investigation into these factors provides an understanding and appreciation of the contextual issues related to the public assimilation and renegotiation of climate change information, as well as the support or rejection of initiatives aimed at addressing climate change. Sub-Saharan African countries are most vulnerable to the effects of climate change because their national economies and populations depend on rain-fed agriculture. Malawi is no exception. The majority of the Malawian population (at least 85%) live in rural areas and depend on subsistence, rain-fed agriculture for their livelihood, and are therefore more vulnerable to climate change. Furthermore, Malawi‘s economy is agro-based (agriculture comprises about 36% of the Gross Domestic Product (GDP), 85% of exports earnings and 84% of total employment). On the basis of these facts, I hypothesised that the perceptions, beliefs and attitudes of Malawians towards climate change are influenced by a wide range of factors, including the impact of climate change on livelihoods. More specifically, I proposed that more rural inhabitants than urban residents were likely to agree that their livelihood has been negatively affected by climate change, and would also be more willing to take voluntary action to address climate change. Upon performing chi-square analyses of the responses, the results indicate that: (i) significantly more rural (91%) than urban inhabitants (51%) agree that their livelihood has been negatively affected by climate change, and (ii) significant higher proportions of the rural population have at some point taken voluntary action to address climate change Multinomial logistic regression models predicted the perceptions, beliefs and attitudes of Malawians towards climate change. The results show that location is the only predictor of whether an individual would agree that his/her livelihood has been negatively affected by climate change or not. Rural inhabitants are 6.5 times more likely than urban residents to agree that their livelihood has been negatively affected by climate change. Location is also a predictor of the belief that climate change and its impact is the will of God; the belief that the solution to climate change rests with God; and how certain or uncertain a person is regarding the effects of climate change. Binary logistic regression results show that location is also the strongest predictor of whether an individual would take a voluntary action to address climate change or not. Rural inhabitants are 2.3 times more likely than urban residents to take voluntary action to address climate change. Besides place of residence, other predictors of perceptions, beliefs and attitudes towards climate change are: level of education (predictor of three outcome variables, namely: how certain or uncertain a person is about the causes of climate change; whether an individual believes that climate change and its impact is the will of God or not; and whether an individual believes that the solution to the problem of climate change rests with God or not); environmental groups and institutions of learning as sources of information about climate change (predictors of how certain or uncertain a person is about the causes of climate change, and whether a person believes that climate change and its impact is the will of God or not, respectively); and the trustworthiness of village headmen as a source of information about climate change (predictor of whether an individual will believe that climate change and its impact is the will of God or not; and whether an individual will take personal initiative to address climate change). These findings affirm the hypothesis that the impact of climate change on livelihoods of Malawians living in rural locations influences their perceptions, beliefs and attitudes towards climate change. Additionally, the findings suggest that public education about climate change remains key to promoting understanding of climate change. The Government of Malawi and non-governmental organisations have to take up this challenge of educating the Malawian public about climate change, particularly those living in rural locations. However, public education of climate change in Malawi demands that we also take into account the contextual factors that influence Malawians‘ perceptions, beliefs and attitudes towards climate change. For future research, the study suggests that more research in Sub-Saharan Africa is warranted to unearth the contextual factors that influence the public understanding of climate change.<br>AFRIKAANSE OPSOMMING: Hierdie studie inkorporeer insigte uit onderskeidelik die tekortskietende/positiwistiese en kontekstuele/kritiese modelle rakende die openbare verstaan van wetenskapsnavorsing, in ‘n poging om die faktore wat die persepsies, oortuigings en houdings teenoor klimaatsverandering in Malawi beïnvloed te ondersoek. Vorige navorsing oor die openbare begrip van klimaatsverandering – wat in die Verenigde State van Amerika (VSA) en Europa uitgevoer is – dui daarop dat individuele persepsies, oortuigings en houdings ‘n invloed uitoefen op die ondersteuning vir beide vrywillige sowel as beleidsinisiatiewe in klimaatsverandering. Dit is egter van groot belang om die faktore wat openbare persepsies, oortuigings en houdings teenoor klimaatsverandering beïnvloed te verstaan. ʼn Ondersoek na hierdie faktore verskaf begrip sowel as waardering vir die kontekstuele kwessies wat verband hou met die openbare assimilasie en ―heronderhandeling‖ van inligting oor klimaatsverandering. So ‘n ondersoek dra ook by tot ‘n verduideliking waarom voorgestelde klimaatsveranderingsinisiatiewe òf verwerp òf ondersteun word. Lande in sub-Sahara Afrika, waaronder Malawi, is baie kwesbaar vir die gevolge van klimaatsverandering as gevolg van die aard van hul ekonomieë en die samelewing se afhanklikheid van nie-besproeiingslandbou. Die Malawiese bevolking is grotendeels landelik (ten minste 85%) en maak staat op nie-besproeiingsbestaansboerdery, wat hulle dus meer kwesbaar maak vir die gevolge van klimaatsverandering. Malawi se ekonomie is boonop landbou-gedrewe: landbou dra by tot ongeveer 36% van die BBP, tot 85% van inkomste uit uitvoere en tot 84% van totale indiensnemingsgetalle. Gegewe hierdie feite is my hipotese dat die persepsies, oortuigings en houdings van Malawiërs teenoor klimaatsverandering deur talle uiteenlopende faktore beïnvloed word, waaronder die impak van klimaatsverandering op hul daaglikse bestaan. Die hipotese suggereer verder dat meer landelike inwoners, in teenstelling tot stedelike inwoners, geneig sal wees om saam te stem dat hul bestaan negatief deur klimaatsverandering beïnvloed word, en derhalwe ook ‘n groter gewilligheid sal openbaar tot vrywillige optrede wat klimaatsverandering aanspreek. Chi-kwadraat analises wat op die opnameresponse uitgevoer is, dui daarop dat (i) meer landelike (91%) as stedelike (51%) inwoners saamstem dat hul bestaan negatief deur klimaatsverandering beïnvloed word en dat (ii) ʼn beduidende hoër persentasie landelike inwoners op een of ander stadium vrywillig teen klimaatsverandering opgetree het. Multinomiale logistiese-regressiemodelle is gebruik om die persepsies, oortuigings en houdings van Malawiërs teenoor klimaatsverandering te voorspel. Die resultate toon dat ligging die enigste betekenisvolle voorspeller is in die uitkoms of ʼn individu saamstem dat sy/haar bestaan negatief deur klimaatsverandering beïnvloed word of nie – dit is 6.5 keer meer waarskynlik dat landelike as stedelike inwoners sal saamstem dat hul bestaan negatief deur klimaatsverandering beïnvloed word. Ligging dien ook as ʼn betekenisvolle voorspeller in drie verdere uitkomste, naamlik die oortuiging dat klimaatsverandering en die impak daarvan die wil van God is, die oortuiging dat die oplossing vir klimaatsverandering by God berus en hoe seker of onseker ʼn individu van sy/haar oortuiging is met betrekking tot die gevolge van klimaatsverandering. Volgens ‘n binêre logistiese-regressieanalise is ligging ook die sterkste voorspeller of ʼn individu vrywillig sal optree om klimaatsverandering aan te spreek, al dan nie. Dit is 2.3 keer meer waarskynlik dat landelike inwoners, in teenstelling met stedelike inwoners, vrywillig sal optree om klimaatsverandering aan te spreek. Agesien van ligging het die volgende ook na vore getree as bykomende voorspellers van individue se persepsies, oortuigings en houdings teenoor klimaatsverandering: (i) vlak van opvoeding (voorspeller van drie uitkomste-veranderlikes: hoe seker of onseker ʼn persoon is oor die oorsake van klimaatsverandering; of ʼn persoon glo dat klimaatsverandering en die gevolglike impak die wil van God is al dan nie; en of ʼn individu glo dat die oplossing vir klimaatsverandering by God berus al dan nie), (ii) die twee bronne van inligting rondom klimaatsverandering, naamlik omgewingsgroepe en opvoedingsinstellings, wat dien as voorspellers van hoe seker of onseker ʼn individu is oor die oorsake van klimaatsverandering, en of ʼn persoon glo dat klimaatsverandering en die gevolglike impak die wil van God is of nie; en (iii) die geloofwaardigheid van stamhoofde as ʼn bron van inligting oor klimaatsverandering (voorspeller van of ʼn persoon sal glo dat klimaatsverandering en die gevolglike impak die wil van God is of nie en of ʼn individu persoonlike inisiatief aan die dag sal lê om klimaatsverandering aan te spreek). Die bevindinge van die studie bevestig die voorgestelde hipotese dat die impak van klimaatsverandering op die bestaan van Malawiërs wat in landelike gebiede woon, ook hul persepsies, oortuigings en houdings teenoor klimaatsverandering beïnvloed. ʼn Verdere bevinding is dat openbare opvoeding oor klimaatsverandering ʼn sleutelrol in die bevordering van die begrip oor klimaatsverandering speel. Die uitdaging rus op die skouers van die Malawiese regering en nie-regeringsorganisasies om die Malawiese publiek, en veral diegene wat in landelike gebiede woon, oor klimaatsverandering op te voed. Die voorgestelde organisasies sal hulself egter nie van hul taak kan kwyt indien daar nie ʼn begrip is van die faktore wat Malawiërs se persepsies, oortuigings en houdings teenoor klimaatsverandering beïnvloed nie. Die studie beveel aan dat meer navorsing in sub-Sahara Afrika onderneem behoort te word om kontekstuele faktore wat die openbare begrip van klimaatsverandering beïnvloed, te identifiseer.

The impact of Typhoon Hagupit has raised public awareness on the hazard of storm surge. The international research and local tide gauge data collected over the years, has shown the trend on sea level rise. From the tropical cyclones and storm surge database of the Hong Kong Observatory, a study on the trends of storm surge impacting Hong Kong (1960~2008) has been carried out to investigate whether significant changes of extreme sea level have taken place under climate changes. The mechanism of storm surge is described in the beginning of this dissertation, followed by clarification of the methods and data used for analysis. It was found that a significant sea level rise was recorded in both Victoria Harbor and Tai Po Kau in the past half century. However, the annual extreme sea level and maximum storm surge of Victoria Harbor had decreased at a rate of 2.6 & 4.8 mmyr-1 (1960~2008). The descending trend are much significant in Tai Po Kau tide gauge station. The trend on storm surge is generally consistent with the decline of tropical cyclones which entered the South China Sea and within the 800km range of Hong Kong. By observing the vibration of sea surface temperature anomolies as Pacific Decadal Oscilliation and El Nino Southern Oscillations, it is possibly related to the annual number of tropical cyclones and affect the chance of intense storm surge impact. The projection on the storm surge intensity at the end of this century has been done in accordance with the result of Global Climate Models in IPCC AR4. The mean sea level is projected to rise for 0.18~0.59m but some of the researchers argue that the value is too conservative. The majority of global cimate models estimate that there is no significant change in the frequency of tropical cyclones but slightly increase in their overall intensity. In using the extreme projection of climate change, the return period of severe storm surge will be significantly shortened at the end of this century. The possibility of extreme sea level, causing serious damage to low lying area in the territority, tends to increase.<br>published_or_final_version<br>Applied Geosciences<br>Master<br>Master of Science

Les bancs de maërl situés dans des écosystèmes côtiers sont soumis à l’impact des changements locaux qui peuvent affecter leur capacité à s’adapter/s’acclimater au changement global (réchauffement et acidification des océans). Malgré l’accroissement de nos connaissances concernant la contribution des algues corallinacées aux cycles du carbone et du carbonate et leur réponse au changement global, un manque de connaissances persiste concernant l’impact qu’elles subissent face aux changements locaux. Les objectifs principaux de cette thèse ont été d’évaluer: i) l’impact du changement local sur trois bancs de maërl situés en milieu tempéré (Bretagne, France) (étude in situ), ii) l’impact de l’acidification et du réchauffement des océans (selon le scénario RCP 8.5, +2.7ºC et -0,3 unités pH) sur trois espèces de maërl, parmi les plus abondantes dans l’Atlantique NE (Lithothamnion corallioides, Phymatolithon calcareum and Lithophyllum incrustans) (étude en laboratoire). Les observations in situ en rade de Brest ont montré l’impact des changements locaux sur l’hétérogénéité et la saisonnalité de la biomasse macroalgale ainsi que sur la production primaire. Les apports d’eau douce par les rivières en rade de Brest exacerbent la dissolution des thalles de L. corallioides à l’obscurité. Les observations au laboratoire ont montré des réponses spécifiques aux espèces avec un impact plus négatif du changement global pendant la saison hivernale par rapport à la saison estivale et un effet interactif des changements globaux avec d’autres paramètres abiotiques tels que la disponibilité en nutriments et l’intensité lumineuse. Les résultats de cette thèse en évidence l’impact des changements locaux d’origine naturelle et anthropique sur le développement, la survie et la capacité des bancs de maërl à s’adapter au changement global<br>Maerl beds located in coastal systems are affected by local changes that may compromise their survival and resilience to global change (ocean warming and acidification). Despite the increasing knowledge regarding the contribution of coralline algae to the carbon and carbonate cycles, and their response to future scenarios of global change, there is a lack of information regarding how they are currently impacted by local changes. This thesis sought to evaluate: i) how three temperate maerl beds (Brittany, France) are impacted by local changes (field study), and ii) how three of the most abundant maerl species in the NE Atlantic (Lithothamnion corallioides, Phymatolithon calcareum and Lithophyllum incrustans) are impacted by ocean warming and acidification (according to the scenario RCP8.5, +2.7ºC and -0.3 pH units) (laboratory study). Field observations in the Bay of Brest showed that the heterogeneity and seasonality of the macroalgal living biomass and primary production is marked by local changes. Freshwater inputs from rivers into the Bay of Brest exacerbated the dissolution of L. corallioides thalli in the dark. Laboratory observations displayed species-specific responses with a more negative impact of global change under winter conditions compared to summer conditions, and an interaction of effects of global change with other abiotic parameters such as nutrient availability and light intensity. The results of this thesis highlight the impact of local changes due to natural and anthropogenic influences on the development, survival and capacity of maerl beds to adapt to global change

Despite numerous debates issue of balancing between global pragmatism, quality of vocational or higher education and its economic utility (recoupment of capital investment in this area) is still essential for many developing countries and transition economies like Ukraine because of predicted by G. Agamben inevitable "global civil war" has already started.

My PhD and post-doctorate researches have focused on paleoclimatic, paleogeographical and paleoenvironmental reconstruction of the Mediterranean Basin and its adjacent seas (i.e. the residual former Paratethys) since 11 Ma. During this time-interval the Mediterranean marine and continental environments were affected by significant paleogeographic changes, forced by global climate and sea-level variability, plate tectonics and regional uplift of Alps s.l. and Carpathians. Two main important events characterize this period: the isolation and evolution of Paratethys and the almost complete desiccation of the Mediterranean Sea, an event known as the Messinian Salinity Crisis. I selected this region because it is very rich in long and continuous sediment archives, which document: (1) climate evolution of the Northern Hemisphere during the Late Cenozoic with respect to vegetation changes, and (2) progressive evolution of initially marine environments towards brackish and freshwater ones. The brackish to fresh environments had a profound effect on the marine organisms (especially dinoflagellates) that responded to the stress by developing a large variety of cyst morphologies, often described as new genera and/or species. Methods. The comparative analysis of pollen grains and dinoflagellate cysts from the same samples is rarely performed for such a long time-interval because it needs a deep knowledge in taxonomy and ecology of the both complementary proxies. I reached this parallel expertise, having the benefit of training in (1) botanical identification of pollen grains from the tropical to boreal zones and their ecological significance by Dr. J.-P. Suc, (2) taxonomy and ecology of dinoflagellate cysts by Pr. M. J. Head. To achieve an understanding of the primary factor inducing morphological variations of dinoflagellate cysts, I developed a biological approach (culturing and growing of present-day living dinoflagellates and inducing stress on microcultures experimentations) under supervision of Pr. J. Lewis (Westminster University, London, UK) and Drs. D. Anderson and D. Kulis (WHOI, USA) during my postdoc appointments. The simultaneous work on living and fossil (using biometry and associated statistical analyses) dinoflagellate cysts has allowed me to initiate the development of a transfer function, widely valid and able for the modelling of the physical parameters of sea-surface waters (salinity, temperature, nutrient contents). Such analyses were performed at high- to very high-chronological resolution, as resulting from the following approach: (1) independently established age-model, based on classical biostratigraphy or radiocarbon ages (for recent sediments), completed by magnetostratigraphy for deposits prior to Mid–Quaternary; (2) comprehensive counting of pollen grains (150 per sample, Pinus or any overabundant taxon excepted) and dinoflagellate cysts (200-300 per sample); (3) interpreting the resulting data with respect to ecological requirements. High- to very high-resolution analyses provides results directly comparable with classical oxygen isotope curves. These signals can therefore also be tuned to the frequency of eccentricity, obliquity and precession cycles. Although palynological proxies can be considered as standard, my integrated approach hoists them at the level of the most competitive methods. Another aspect consists in its present-day background, based on many surface samples from the Mediterranean, Marmara and Black seas, taken during several cruises and sampling parties at IFREMER-Brest and WHOI. To develop parallel analyses of pollen grains and dinoflagellate cysts offers additional considerable interests, such as (1) continuous records of climatic changes and sea-level variations independently from sediment types, and (2) quantifications (using transfer functions) of climate for both continental and marine (to brackish) realms as well as of physical oceanic parameters (SST, SSS, nutrient content etc.).<br /><br />Results and research in progress<br />Using pollen grains analysis, I developed investigations on vegetation dynamics and paleoclimate reconstructions for the whole Mediterranean region and Western Europe extended to the Late Cenozoic (Jiménez-Moreno et al., 2007; Fauquette et al., 2006). Thanks to the high-chronologic resolution: <br />a. I established the response of regional vegetation to eccentricity forcing in SW Romania (Dacic Basin) and Black Sea (DSDP Site380) whatever the sediment types (Popescu, 2001, 2006; Popescu et al., 2006a);<br />b. I was the first to demonstrate the precession forcing on regional vegetation (Popescu et al., 2006b) through the Lupoaia pollen record (SW Romania);<br />c. in the frame of two PhD theses that I co-supervise, pollen grain and dinoflagellate cyst records from DSDP Site 380 (7 - 4 Ma) were completed from 4 Ma to Present in order to evidence the impact of glacial-interglacial cycles over the regional vegetation and to reconstruct the climate variability for the last 7 Ma;<br />d. I was the first to demonstrate the solar cycles forcing (Hale and Gleissberg cycles) on the regional vegetation (through the “Thermophilous trees / Artemisia” ratio) since the Last Glacial Maximum were evidenced in cored sediments from the Black and Marmara seas (unpublished data), that is a unique outcome. <br />Using the biometric approach on the dinoflagellate cysts in association with statistical analyses, I demonstrated that fluctuations in salinity are partially responsible for modifying size, shape and ornamentation of the cysts, providing the first reliable paleoecological and paloebiogeographic reconstructions of the brackish Paratethyan basins (Popescu et al., palynology , in press). <br />Simultaneously, I performed experimental cultures on a living-dinoflagellate species (Scrippsiella trifida): suggested relationships between cyst morphological variations and stress under controlled salinity are confirmed by the preliminary results, while reproduction rate seems also modified (unpublished data). <br />The multi-proxy (palynology, sedimentology and geochemistry) study on the Aral Sea, done by the first PhD student that I co-supervised, allowed not only the reconstruction of the regional paleoclimate and paleoenvironments, but also permitted to understand the atmosphere dynamics of the last 2 ka over the high latitudes (Sorrel et al., 2006, 2007). <br />Hence, my palynological and biological expertise offers an exclusive tool for establishing a continuous high resolution chronology, paleoclimatic, paleobiogeographic and paleoenvironmental reconstructions. This is particularly important for the basins impacted by important environmental changes, such as the Mediterranean and Black seas, the sediments of the latter being precisely dated for the first time by this approach.<br /><br />I do no want to close this Introduction Section without addressing my largest acknowledgements to those who supported my researches and expressed their interest in my project, providing personal grants and/or financial assistance for achieving my researches, and especially the PhD and master – graduation students that I appreciated so much to co-supervise.

Дослідено ключові виклики й зміни у сфері менеджменту (зокрема корпоративного) ті інноваційний інструментарій в умовах гібридної роботи.<br>The key challenges and changes in the field of management (including corporate) and innovative tools in the context of hybrid work are studied.

Although the central nervous system (CNS) was once considered an immunologically privileged site, in recent years it has become increasingly evident that cross talk between the immune system and the CNS does occur. As a result, patients with chronic inflammatory diseases such as rheumatoid arthritis, inflammatory bowel disease or psoriasis are often further burdened with neuropsychiatric symptoms such as depression, anxiety and fatigue. Despite the recent advances in our understanding of neuroimmune communication pathways, the precise effect peripheral immune activation has on neural circuitry remains unclear. Therefore, the primary aim of this thesis was to develop a better understanding of the bidirectional relationship, and communication pathways, that exist between the immune system and the nervous system. By utilising transcriptomics in a well-characterised murine model of systemic inflammation, I have investigated the molecular mechanisms by which inflammation originating in the periphery can induce transcriptional modulation in the brain. Systemic inflammation was induced in male C57BL/6 mice via intraperitoneal injection of lipopolysaccharide (LPS). After 48 hours, whole brain transcriptional profiles were assessed, and compared to that of a vehicle- treated control group, using Affymetrix GeneChip microarrays. Target gene induction, identified by microarray analysis was validated independently using QPCR. Expression of the same panel of target genes was then investigated, in the brains of mice, following the induction of different sterile, and TLR- dependent, models of peripheral inflammation. Microarray analysis of whole brains collected 48hr after LPS challenge revealed increased transcription of a range of interferon-stimulated genes (ISGs) in the brain, including a significant upregulation of the classic interferon-induced chemokine CXCL10. This transcriptional profile could not be reproduced by the systemic administration of TNFα, or following lipoteichoic acid-induced systemic inflammation. However, target genes remained induced in the brain following daily LPS injections, in the absence of a detectable inflammatory cytokine response in the periphery. 1 The central induction of CXCL10 suggests that acute exposure to LPS in the periphery may prime the brain for T cell infiltration. This prompted an investigation into whether leukocytes infiltrated the brain following daily systemic LPS injections. First, the inflammatory chemokine repertoire in the brains of LPS treated mice was systematically characterised. In addition to Cxcl10, repeated injection of LPS in the periphery triggered a transient increase in the transcription of a number of other inflammatory chemokines in the brain. Chemokine induction was associated with an influx of leukocytes from the periphery, and an increase in mRNA encoding the relevant chemokine receptors. Therefore, chemokine induction in the brain following daily systemic LPS injections may mediate the recruitment of leukocytes from the periphery. The transcriptional response in the brain following systemic LPS challenge is indicative of a peripherally triggered inflammatory response in the brain. The data described in this thesis highlight a potential mechanism of gene modulation in the brain which may be dependent on a TLR-induced type I interferon response. Considerable evidence links type I interferons to psychiatric disorders, and consequently, interferon production in the brain could represent an important mechanism linking peripheral TLR-induced inflammation with behavioural changes. In addition, the data described in this thesis demonstrate that chronic exposure to LPS in the periphery may remotely modulate the recruitment of leukocytes to the brain. This highlights a potential protective mechanism that could prevent a chronic bacterial infection from spreading from the periphery to the brain.

Extreme sea levels exert a major control over the coastal zone, and many studies have found that they are changing at locations around the world. This thesis tests the assertion that these changes are predominantly caused by the global rise in mean sea level by investigating the importance of variability, over a range of timescales, in the other main components of sea level. The analysis is undertaken using a quasi-global dataset of 220 tide gauge records that range in length from 28-164 years. For the first objective, secular (linear) trends in 15 different tidal levels were found to be significant (95% confidence) at between 34% and 63% of the study sites, depending on the tidal level analysed. Significant trends were distributed at sites around the world and at 37 sites the magnitude of the trends was over 1 mm/yr, comparable to the rise in global mean sea level over the 20th century. Spatial patterns were observed on local, regional and global scales. The global rise in mean sea level may be the cause of significantly more positive trends than negative trends occurring in high water levels, but other mechanisms appear more important at many locations. The second objective assessed changes in the meteorological component of sea level. Significant tide-surge interaction was found at 59% or 81% of the 220 study sites, depending on the method used. At locations that have significant tide-surge interaction skew surge is the better parameter for the representation of the meteorological component. Only 13% of sites had significant secular trends in skew surge. There were significantly fewer negative trends in skew surge than the non-tidal residual, which may be because the influence of phase offsets is removed when using skew surge. Inter-annual variability in skew surge is large, but strong correlations between different regional skew surge and climate indices were not found to be significant in this thesis. The third objective evaluated how the variability in the tidal and meteorological components of sea level - together with changes in mean sea level - influenced seasonal, inter-annual and secular changes in extreme sea levels. Variability in baseline extreme sea level (i.e. timescales greater than 6 months) was dominated by secular changes in mean sea level and the seasonal and inter-annual variability in mean sea level and skew surge, at most sites. The combined magnitude of the extracted signals reached 2.4 m in the North Sea, but was typically between 0.8 and 1.2 m. Changes in the relative phase of each signal, as well as the magnitude, may alter the magnitude of extreme sea levels. If independent signals in different components and timescales occurred in phase then the baseline extreme sea levels would increase at all sites in this study. This thesis presents novel findings that show that while secular trends in mean sea level are important to changes in extreme sea levels, significant changes are occurring in all components and over many timescales. Shifts in both the magnitude and phase of signals in all components and over all timescales should be considered in extreme sea level projections. Accurate calculation of extreme sea levels has important implications for applications in the coastal zone, including flood defence, navigation, energy extraction and habitat protection.

Global changes resulting from human activities, including elevated levels of greenhouse gases, enrichment of nitrogen and land use changes, have led to substantial losses in biodiversity of macroscopic organisms, such as plants and animals, but whether these changes will have similar impacts on microscopic organisms, such as bacteria and fungi, is less clear. I examined the impact of three of these global changes, including elevated carbon dioxide, increased soil nitrogen availability and large-scale deforestation, on the biodiversity of soil fungi in three separate ecosystems. The responses of fungi to global changes were variable across ecosystems and the experimental system and were not readily predicted by observed changes in the plant community. However, subtle shifts in the community composition of fungi were observed in response to all global changes. Whether these shifts will impact the ecosystem function of these systems in unclear, but previous studies suggest that even small changes in community dynamics can have large effects on important processes, such as nitrogen cycling and carbon storage. These findings indicate that soil fungi do respond to global changes, but additional research must be undertaken to examine the effects of these shifts.<br>10000-01-01

This research aims at understanding how human driven global environmental changes in terms of climate and land use are expected to affect the spatial and temporal distribution of water resources. The main questions that thesis asks are: (1) how global climate and land use change are expected to impact the spatial and temporal distribution of the water resources. (2) How human activities like hydropower and agricultural production are likely to be impacted by global environmental changes. (3) How different socio-environmental systems could be adapted to the changing conditions. The thesis is organized in a set of studies aimed at estimating the main practical consequences in terms of hydropower and agricultural production at different geographical scale. It does so selecting the most appropriate tool, from the two main categories of statistical analysis and physical modeling, for each of the specific case studies. A statistical model is utilized to assess the sensitivity of the global hydropower generation to variations in climate. A biosphere model integrated with a routing scheme is utilized to assess the impacts of climate and land use change on the hydrology of the Tapajos river basin, a portion of the Brazilian Amazon. A hydro-energy model was used to assess the possible implications in case of hydropower development in the river system. A crop model was used to analyze the expected impacts to the agricultural productivity in the upper part of the Tapajos basin, one of the most important areas for this economic sector in Brazil. Results show how the global hydropower system is expected to be vulnerable to global changes with specific magnitudes linked to the spatial distribution of climate change and the specific characteristics of the power plants. The Tapajos river basin hydrology is expected to be seriously impacted by climate change, mainly through a delay in the beginning of the rainy season and a reduction of its duration. Land use change, in the specific case deforestation, is expected to partially invert the decreasing trends in river discharge caused by climate change, but causing a consistent increase in flow variability. Moreover, the crop analysis confirmed the expected negative climate change impacts on the agricultural sector in the upper part of the basin, creating the basis for a possible demand for irrigation: an adaptation strategy destined at increasing the anthropogenic pressure on the water resources. The project aims at providing policy makers with a better understanding of the expected future impacts and enhances long-term adaptation strategies. The global hydropower analysis gives an idea of the patterns of vulnerability of this system of production. The basin scale analysis shows how the river flow could be modified by the combined effects of climate, land use change and alternative uses water demand. This confirms that an increasing level of uncertainty should be taken into consideration in case of infrastructural development of the area. This thesis provides a significant contribution to the debate about uncertainty and stationarity in water management. It proves, providing practical examples, how different socio-economic and ecological systems at different geographical scale are interconnected: the dynamics influencing one system affect, directly or indirectly, the connected systems causing a cascade effect.

Rising carbon dioxide (CO2) concentrations in the atmosphere will increase the average pCO2 level in the world oceans, which will have a knock-on effect on the marine ecosystem. Coastal seagrass communities one of the most productive marine ecosystems are predicted to benefit from the increase in CO2 levels, but long-term effects of elevated CO2 on seagrass communities are less understood. Population reconstruction techniques was used to investigate the population dynamics of Cymodocea nodosa meadows, exposed to long term elevated CO2 at volcanic seeps off Greece and Italy. Effect of elevated CO2 was noticed on the growth, morphometry, density, biomass and age structure at CO2 seeps. Above to below ground biomass ratio of C. nodosa were higher at CO2 seeps than at reference sites. The plastochrome interval were similar at all CO2 seeps. The shoot age and shoot longevity of plants were lower at seeps than reference sites. The present recruitment (sampled year) of the seagrass were higher than long-term average recruitment of the communities near the seeps. Carbon to nitrogen ratios (%DW) of C. nodosa were higher in leaves at seeps. Annual leaf production was higher near the seeps. This study suggests increased production of C. nodosa under elevated CO2 levels, but other co-factors such as nutrients, trace metal toxicity must also be taken into consideration while predicting effects of future CO2 concentrations. Volcanic CO2 seeps are now being used as natural analogues for ocean acidification studies although these areas can be affected by trace element input and may alter ecosystem responses to gradient in carbonate chemistry. Here Fe and a range of trace elements (Cd, Co, Cu, Hg, Mn, Pb, Ni and Zn) were analysed from sediments and from the roots, rhizomes and leaves of seagrass at six CO2 seeps and reference sites off Greece and Italy. There were higher metal levels in sediment and seagrasses at all CO2 seeps than reference sites. Sediment Quality Guideline Quotient, a commonly used pollution index, indicated that some of the metals (Cd, Cu, Hg, Ni) were in high enough concentrations to have adverse biological effects, such as Cu at Ischia site and Hg at Vulcano. Higher accumulation of elements from sediments in roots and leaves at CO2 seeps were found from Bio Sediment Accumulation Factor index. There were higher levels of Cu, Fe, Mn and Zn in leaves and rhizomes for P. oceanica and higher levels of Cd, Co, Cu, Fe and Zn in C. nodosa compartments at CO2 seeps. Fe and Mn were found with positive correlation within sediment-roots and sediment-rhizomes, whereas Cd, Co and Pb were found with positive correlation in compartments of C. nodosa. In P. oceanica positive correlation were only observed for Cd within sediment-roots and plant compartments. Low pH and ocean acidification increased the concentration of elements at CO2 seeps than reference sites. Thus, caution is needed, when using volcanic seep systems as analogue for the effects of rising CO2, as metals can reach levels that are toxic to seagrass, masking any potential benefits of increased levels of carbon dioxide for seagrass productivity. Net community production (NCP) and community respiration (CR) were measured under air exposed and CO2 enriched conditions for intertidal Z. noltei meadows and unvegetated sediment communities during emersion in summer and winter seasons. Community production and respiration were measured in-situ using benthic chambers. CO2 flux under air and CO2 enriched conditions were measured over a series of short term incubations (30min) using an infra-red gas analyser. Incident photosynthetic active radiation (PAR) was recorded during the incubations covering the daily and seasonal variation. Linear regression model was used to test the effects of irradiance on net community production. NCP of Z. noltei community were higher under CO2 enriched conditions than air exposed conditions in both summer and winter seasons. There was no effect of CO2 on the CR rate of Z. noltei community in summer season. NCP of sediment community were higher in summer season and winter season under CO2 enriched conditions. Sediment CR rates were higher in winter than summer season. The light compensation point of Z. noltei and sediment community were lower in both seasons under CO2 enriched conditions. Seasonal budget of community production was higher in Z. noltei than sediment communities. A clear effect of PAR was noticed on the net community production of both communities. Higher PAR intensities resulted in higher NCP under CO2 enriched conditions for both communities. CO2 enrichment will have a positive effect on the intertidal communities during emersion.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics; and, (S.B.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2011.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 59-60).<br>A recent article by Kidston et al. [8] demonstrates that the length of atmospheric eddies increases in simulations of future global warming. This thesis expands on Kidston et al.'s work with additional studies of eddy length in the NCEP2 reanalysis (a model-data synthesis that reconstructs past atmospheric circulation) and general circulation models (GCMs) from the Coupled Model Intercomparison Project phase 3. Eddy lengths are compared to computed values of the Rossby radius and the Rhines scale, which have been hypothesized to set the eddy length. The GCMs reproduce the seasonal variation in the eddy lengths seen in the reanalysis. To explore the effect of latent heating on the eddies, a modification to the static stability is used to calculate an effective Rossby radius. The effective Rossby radius is an improvement over the traditional dry Rossby radius in predicting the seasonal cycle of northern hemisphere eddy length, if the height scale used for calculation of the Rossby radius is the depth of the free troposphere. There is no improvement if the scale height is used instead of the free troposphere depth. However, both Rossby radii and the Rhines scale fail to explain the weaker seasonal cycle in southern hemisphere eddy length. In agreement with Kidson et al., the GCMs robustly project an increase in eddy length as the climate warms. The Rossby radii and Rhines scale are also generally projected to increase. Although it is not possible to state with confidence what process ultimately controls atmospheric eddy lengths, taken as a whole the results of this study increase confidence in the projection of future increases in eddy length.<br>by Todd A. Mooring.<br>S.B.

The key to understanding the future impact of the anthropogenic combustion of fossil fuels on the climate system, is to fully understand the complex feedback loops within the natural Earth system. One natural climate feedback that has been proposed is the Coral Reef Hypothesis whereby significant increases in coral reef growth may have contributed to the deglacial increase in atmospheric CO2 observed in the ice core records. This thesis examines the role of coral reefs in the oceanic carbonate budget and global carbon cycle both spatially and temporally during the Holocene. Using the most comprehensive reef area estimate to date, a conservative estimate of cumulative CaCO3 accumulation within coral reefs globally from 10 kyr BP to present is 7970 Gt. This estimate includes a temporal and spatial view of reef CaCO3 accumulation during the Holocene and represents coral reefs alone, whereas previous budgets have included wider neritic carbonate facies. This mass of reefal CaCO3 accumulation would have made approximately 2100 Gt CO2 available for release to the atmosphere over the Holocene. Radiocarbon dating of coral obtained from new drill cores from Rodrigues (Southwest Indian Ocean), Lizard Island and MacGillivray Reef (Northern Great Barrier Reef (NGBR)), helps to reveal the spatial and temporal pattern of Holocene CaCO3 accumulation within these reefs and contributes to the dataset compiled to calculate the global mass balance of coral reef carbonate. The new data presented here demonstrates that the reefs at Rodrigues, like those at Reunion and Mauritius only reached a mature state (reached sea level) by 2 to 3 ka – thousands of years later than most of the reefs in the Australasian region. The windward margins at Lizard Island and MacGillivray Reef started growing ca 6.7 and 7.6 cal kyr BP respectively directly on an assumed granite basement and reached sea level approximately 4 and 5.6 cal kyr BP respectively. The leeward margin at MacGillivray Reef was initiated by 8.2 cal kyr BP directly on a granite basement, only reaching sea level relatively recently between 260 and 80 cal yr BP. The absence of Pleistocene reefal deposits indicates the possibility that the shelf in this region may have subsided relative to modern day sea level by at least 15 m since the last interglacial (125 ka). The role of the calcareous green alga Halimeda in the marine carbonate budget is still unknown both spatially and temporally for the Holocene. Here a quantification of the carbonate mass within the ribbon reefs and Halimeda bioherms on the outer shelf of the NGBR is presented. It is estimated that Halimeda bioherms contain at least as much (possibly 400 % more) CaCO3 sediment than the adjacent ribbon reefs within the NGBR province.

Thesis (Ph. D.)--University of California, San Diego, 2006.<br>Title from first page of PDF file (viewed June 26, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 177-192).

O presente estudo tem por objetivo investigar mudanças no padrão de internacionalização de empresas Born Global. Alguns aspectos da internacionalização – tais como motivações, critérios para seleção de países e modos de entrada – foram analisados, bem como fatores que possam ter impulsionado mudanças na atuação internacional. Por fim, foi investigado se as empresas continuam com uma lógica de expansão, como nos primeiros anos, ou se estão tendendo para uma consolidação de posições. A revisão da literatura concentrou-se em elementos teóricos da internacionalização de pequenas empresas – empreendedorismo internacional e o modelo de Effectuation – além de estudos sobre evolução organizacional sob a perspectiva de Punctuated Equilibrium. Como a evolução das empresas Born Global é um fenômeno ainda pouco estudado (tendo a literatura sobre essas empresas se concentrado basicamente nos estágios iniciais de sua internacionalização), optou-se por realizar um estudo qualitativo com uma amostra de julgamento composta por três empresas, as quais atendiam aos critérios citados na literatura para caracterização de empresas como Born Global. Foi possível observar que, mesmo após vários anos após sua investida inicial no mercado internacional, a empresa pode continuar em expansão, embora haja uma tendência de apresentar também uma lógica da consolidação. Elas não buscam apenas o simples crescimento, mas rentabilizar os resultados, bem como vem utilizando critérios mais seletivos para a aceitação de clientes, seleção de países e tomada de decisões sobre o modo de operação no exterior. Como aplicação ao mundo empresarial, este estudo evidencia a busca por uma operação que minimize custos, o aproveitamento de oportunidades que podem ser de curto prazo, a atuação junto a parceiros (networks) e a receptividade para fusões ou aquisições.<br>This study aims to investigate changes in the pattern of internationalization of Born Global companies. Some aspects of globalization - such as motivations, criteria for country selection and entry modes - were analyzed, as well as factors that may have driven changes in international operations. Finally, we investigated whether companies continue with a logical expansion, as in former years, or are trending toward a consolidation of positions. The literature review focused on theoretical elements of internationalization of small businesses - international entrepreneurship and the model of effectuation - and studies of organizational change from the perspective of Punctuated Equilibrium. How the evolution of Born Global companies is a little studied phenomenon (with the literature on these companies basically concentrated in the early stages of internationalization), we chose to conduct a qualitative study with a sample of trial consists of three companies, the which met the criteria cited in the literature to characterize companies like Global Born. It was observed that, even after several years after its initial foray into the international market, the company can continue to expand, although there is a trend also present the logic of consolidation. They seek not only the simple growth but profitable results, and have been using more selective criteria for customer acceptance, selection of countries and making decisions on the mode of operation abroad. As an application to the business world, this study highlights the search for an operation that minimizes costs, take advantage of opportunities that may be short-term relationships with select partners (networks) and receptivity to mergers or acquisitions.

Thesis (M.S.)--Massachusetts Institute of Technology, Sloan School of Management, 1996, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1996.<br>Includes bibliographical references (p. 95-96).<br>by William B. Householder.<br>M.S.

From the Pliocene to the modern, the Earth’s climate has undergone a vast and significant change from a world dominated by continental ice restricted only to Antarctica with a rhythmic 41 kyr beat, through a period of declining atmospheric CO2 and cooling culminating with the bihemispheric glaciation known today, dominated by 100 kyr cyclicity. Ocean circulation is often given a central role in the dynamics of the late Neogene although many questions, such as the role of the North Atlantic in glacial-interglacial CO2 change remain. It is a well-studied region however and as such provides an ideal location for further study with novel proxies that may potentially provide new insights. Similarly, atmospheric CO2 is often thought to be the most crucial single variable driving Plio-Pleistocene climate change. Atmospheric CO2 reconstructions so far published beyond the end of the 800 ka Dome C ice core record are however few and of relatively low resolution and/or precision. This is at present hampering our understanding of CO2-climate interaction for climates warmer than the present and must be addressed as a priority given humanity’s ever-increasing CO2 emissions and anthropogenic global warming. This thesis aims to address these issues using boron-based proxies in foraminiferal carbonate. The potential power of these boron based proxies to directly quantify the marine carbonate system in the past has an enormous draw, both as a pH-CO2 proxy, but also for identifying the role of the deep ocean circulation changes in ocean carbon storage and release on orbital timescales. The first half of this thesis aims to better address the role of ocean circulation in rapid climate change and carbon storage over glacial-interglacial cycles. δ11B and B/Ca records from benthic foraminifera (Cibicidoides wuellerstorfi) from three cores in the North Atlantic spanning the last full glacial cycle and making up a depth, latitude and longitude transect are presented. These show that over this period, North Atlantic circulation is both dynamic and complex, presenting new and demonstrable links between climate change and the deep ocean carbonate system. Within this record a high-resolution section was taken focusing on the last 40 thousand years to search for any rapid changes in circulation associated with Heinrich events. It is demonstrated here that the boron based proxies can remove ambiguity from the existing records of deep ocean circulation change and challenge the established theory of deep water formation (DWF) shutdown in the Northern hemisphere during H-events. In the second half of this thesis atmospheric CO2 records, beyond the reach of the ice cores, derived from the δ11B of planktonic foraminifera (Globigerinoides ruber) from the tropical Atlantic basin and Caribbean Sea are presented. Here the relationship between the climate system (both in terms of ice-volume/sea level and temperature) is examined in climate states warmer than today. These include a suborbitally resolved record from 1.0-1.2 Ma to observe the nature of CO2 cycles before the ‘over thickening’ of the Laurentide ice sheet and the associated switch from 41 kyr to 100 kyr climate cycles at the Mid Pleistocene Transition (MPT). This study reveals the existence, around 1 million years ago, of high amplitude CO2 cycles with a 41 kyr cyclicity, and a mean CO2 level around 25 ppm above the Late Pleistocene. The relationship between CO2 and ice volume/SL prior to the MPT is significantly different to that post MPT, implying that CO2 decline and some other boundary condition change, probably related to the sub-glacial regolith, were both responsible for this most recent major climatic transition. Also reconstructed is a multisite reconstruction of atmospheric CO2, extending through the last 3.5 million years, including the onset of Northern Hemisphere Glaciation (iNHG). In order to gain a quantitative understanding of the role of CO2 decline in Plio-Pleistocene cooling a comprehensive compilation of sea surface temperature data is also presented. A combination of this record of “global” sea surface temperature data with the longterm CO2 data confirms that Plio-Pleistocene cooling was driven by CO2 decline amplified by the ice-sheet albedo feedback.

La physiologie, le comportement et la distribution des insectes sont grandement influencés par la température. La compréhension de la réponse des insectes à la température permet de développer de modèles capables de simuler leurs dynamiques spatio-temporelles. De tels modèles représentent des outils intéressants afin d’améliorer le contrôle intégré des ravageurs car ils permettent d’identifier les risques liés a ces espèces. La présente étude a pour objectif de développer plusieurs stratégies de modélisation de la distribution et propagation de ravageurs invasifs de la pomme de terre dans la région Nord andine. D’abord, nous avons développé un automate cellulaire simulant la dynamique d’invasion des ravageurs en prenant en compte l’influence de l’activité anthropique sur la propagation. Ensuite, nous avons développé des modèles capables de simuler l’influence de l’hétérogénéité thermique et de simuler les dynamiques en présence de jeux de données limités. Enfin, nous avons construit un modèle individu centré permettant de simuler les dynamiques en réponse à la température. Ce modèle nous a permis de réaliser des cartes de risque présent et futur d’invasion à l’échelle de la région Nord-andine. Ce travail montre l’importance de l’hétérogénéité environnementale et sociale sur la propagation des ravageurs. Les modèles développés dans cette thèse pourront être appliqués dans des programmes de contrôle intégré des ravageurs afin de présenter aux agriculteurs de la région les risques d’évolution de l’infestation en relation avec leurs pratiques culturales et les changements globaux.

Movement is impossible without contraction of muscles which incurs expenditure of metabolic energy. This energy cost decreases as people become more skilled, ie, more energetically efficient. The mechanisms whereby people achieve this improved efficiency remain unclear. Hence, the current study examined how task performance, coordination, muscle activation and energy expenditure change with increased skill. Ten participants (6 M, 4 F) attended 2 pre-practice, 10 practice and 2 post-practice sessions that comprised 1) tests of arm V̇O2 peak and submaximal leg fitness; and 2) bimanual coordination tasks of arm cycling at a workload of 20% peak V̇O2. Three relative phases of coordination (0°, 180°, 90°) and four cadences (25, 50, 75, 100 rpm) were studied. Oxygen consumption, heart rate, electromyography (EMG) of 24 muscles and ratings of perceived exertion (RPE) were recorded. A secondary choice reaction time (RT) task assessed attentional load. Practice of arm cycling led to significantly improved accuracy, stability and energetic efficiency for all cadences and coordination modes. Increases in gross efficiency (~10%) and power output were accompanied by reductions in RT and RPE. Activation of brachialis, biceps brachii, and pectoralis major muscles was increased bilaterally post-practice, while other muscles showed no change. Differences in activation between phases were also found bilaterally in extensor digitorum, pectoralis major, anterior deltoid, and posterior deltoid. The increase in gross efficiency was consistent with the participants producing more power for the same energy input after practice. Further, different patterns of muscle recruitment at different relative phases imply coordination changes with task difficulty (different relative phases). Energy cost increased with task difficulty while accuracy and stability of coordination deteriorated. The changes in the EMG patterns, levels and timing with practice were presumed to optimise movement economy.

L'innalzamento del livello del mare è una delle principali conseguenze del riscaldamento globale dovuto all'emissione di gas serra in atmosfera ed è quindi di cruciale interesse nello studio dei cambiamenti climatici. L'obiettivo di questa tesi di Dottorato consiste nell'analisi dell'importanza relativa dei vari processi che contribuiscono al cambiamento del livello del mare durante l'ultima decade del 20° secolo e il primo decennio del 21° secolo, mediante l'utilizzo di un modello numerico globale di circolazione oceanica ad alta risoluzione (1/4°). Lo studio è stato in seguito esteso nel futuro, fornendo proiezioni del cambiamento del livello del mare nei prossimo 20 anni e concentrando la nostra analisi sulla regione delle Piccole Isole del Pacifico, che rappresenta una delle aree più vulnerabili agli impatti legati all'innalzamento del livello del mare. Inoltre, la risposta dell'oceano a stime realistiche di scioglimento dei ghiacciai continentali di Antartide e Groenlandia, ricostruite a partire da dati gravimetrici e di modelli atmosferici, è stato investigato, essendo questa una delle principali cause del cambiamento del livello del mare.<br>As a major effect of anthropogenic greenhouse gases induced global warming, sea level rise is a key climate issue of crucial interest in the frame of climate change investigation. The aim of this Ph.D. thesis is to study the relative importance of the different processes that contribute to sea level change during the last decade of the 20th century and the first decade of the 21st century, by using an eddy-permitting Ocean General Circulation Model at a spatial resolution of 1/4°. We have further extended our analysis in the future, by providing projections of sea level change for the next 20 years at an unprecedented resolution of 0.25°, with particular focus on the Pacific Small Island region, which represents a highly vulnerable region to the impacts of sea level rise. The exchange of water between the ocean and Greenland and Antarctica ice-sheets is one of the major causes of sea level change. For this reason, the response of the ocean to a realistic ice-sheets runoff, reconstructed through a combination of gravimetric and atmospheric model data, has been investigated.

The Permian has been the theatre of major global changes in the Earth’s geodynamics, climate, seawater and atmosphere geochemistry, and thus it represents an interesting case study to understand the response of organisms to environmental changes, a topic which is of increasing interest to the scientific community, who has to face the current global change. In fact, in the Permian the biotic response was dramatic, culminating at the end of the period with the greatest mass extinction of the Phanerozoic. Noteworthy, the end Permian mass extinction coincided with one of the largest known continental eruptions, the Siberian trap basalts, that are considered to have generated more than 100,000 Gt of CO2 as well as CH4, leading to ocean acidification and global warming. Brachiopods, which are low buffered organisms with a heavily calcified shell, can be the perfect candidates to record the trends related to changes in seawater chemistry during this critical interval. The aim of this research is thus to study the biomineralization of brachiopod shells to unravel the patterns of biotic changes caused by the extreme Late Permian events. To reach this goal, I organized my research in three different phases, starting to investigate the main differences in the shell fabric of the brachiopod groups ruling the benthic communities in the Late Permian, that are the classes Rhynchonellata and Strophomenata (phase 1); then comparing the stratigraphic distribution of brachiopod genera during the Late Permian in a paleogeographic perspective (phase 2); finally, analyzing in great details, both qualitatively and quantitatively, the shell fabric of several taxa from Tethyan Permian-Triassic Boundary (PTB) successions, to unravel the biomineralization activity at generic level(phase 3). To develop this research I investigated brachiopods belonging to different paleogeographic localities in the Tethyan realm. The specimens were in part collected by myself during field activity, in part already available from the collections of Dipartimento di Scienze della Terra “A. Desio” and also provided by external partners. The studied brachiopods come from: 1. Nesen Formation, Alborz Mountains, northern Iran; 2. Julfa Formation, Ali Bashi Formation and Boundary Clay, Ali Bashi Mountains, Northwestern Iran; 3. Selong Group, southern Tibet; 4. Gyanyima Formation, southwestern Tibet; 5. Bulla Member, Dolomites, Northern Italy; 6. Gomaniibrik Formation, Hazro, Turkey; 7. Changhsing Limestone and Dalong Formation, South China These data were integrated with the analysis of the available published literature on Upper Permian brachiopods, in particular to develop step 1 and 2. The methods used to develop this research may be grouped in four main categories: 1. Microscopical analysis of the shell structure using SEM (phases 1 and 3) 2. Geochemical analysis of the calcitic shell contents for trace elements (Mg, Sr, Fe, Mn) and stable isotopes (C and O)(phase 1) 3. Image analysis to acquire quantitative parameters of the shell ultrastructure (phase 3) 4. Statistical analysis of the stratigraphic distribution of brachiopod taxa using the logistic regression in order to test association between environmental variable and taxonomic composition (phase 2). Performing phase 1, I discovered important differences in the structural and chemical composition of the shell in the two main Upper Permian brachiopod classes: the Strophomenata and the Rhynchonellata. These taxa bear a different calcitic shell fabric: the former possesses a double or triple layer shell consisting of a primary layer, a secondary layer with cross-bladed laminae and a prismatic tertiary layer; the latter have a shell succession similar to extant ones, which is composed of a primary layer of crystallites, a secondary layer of discrete fibers and, eventually, a tertiary layer of prisms. Their different fabric corresponds to differences in the chemical composition. In particular the Strophomenata, which have a laminar fabric enriched in organic compounds, have higher Sr and Mg contents and a lower δ13C in their shells than co-occurring Rhynchonellata. In phase 2, the logistic regression analysis has shown that important changes in terms of taxonomic composition took place from the Wuchiapingian to the Changhsingian, with the Strophomenata being the dominant group in terms of abundance, but the Rhynchonellata being more prone to high rank diversification. In phase 3, the detailed study of the shell structure at the SEM, has revealed that Upper Permian genera can produce different type of shells, especially regarding the ratio between the organic and inorganic content. In particular, the taxa occurring during the first part of the Late Permian (Wuchiapingian and early Changhsingian) biomineralized thick shells with a relatively high inorganic content. Instead, in the late Changhsingian, brachiopod taxa produced shells with a higher organic content. In addition, the quantitative analysis of the fabric, based on the measured size of its structural units, revealed different trends in the two classes. Rhynchonellata reduced the size of the structural units (fibers) of their shell as approaching the PTB. On the other hand, the Strophomenata show a more complex response, either continuing in their normal biomineralization activity or increasing the size of their structural units (laminae). Through this research, two important conclusions were reached: the first concerns the paleobiological implications of the different biomineralization processes performed by brachiopods, and the second is related to the brachiopod response to the end Permian global environmental changes. It is now clear that the brachiopod classes of Strophomenata and Rhynchonellata have profound differences in terms of the structural and elemental composition of their shell. These differences are likely related to the biomineralization process responsible for the formation of their shell, a collective process where arrays of mantle cells secrete the biocomposite in the Strophomenata, versus a discrete, single cell driven process in the Rhynchonellata . The observed changes in brachiopod shell biomineralization in the latest Permian are compatible with a change in the carbonate saturation state of seawater and thus with ocean acidification, related to Siberian Traps flood basalt volcanism. In fact, a general trend toward production of calcitic shells with higher organic content is recorded up to the PTB in most brachiopod groups. This may have been likely the result of changes in the physical and chemical composition of seawater that produced an increase in the energetic cost for carbonate precipitation in low buffered organisms such as brachiopods.