147 research outputs found
Impacts and State‐Dependence of AMOC Weakening in a Warming Climate
No full textAbstract All climate models project a weakening of the Atlantic Meridional Overturning Circulation (AMOC) strength in response to greenhouse gas forcing. However, the climate impacts of the AMOC decline alone cannot be isolated from other drivers of climate change using existing Coupled Model Intercomparison Project simulations. To address this issue, we conduct idealized experiments using the EC‐Earth3 climate model. We compare an abrupt 4×CO2 simulation with the same experiment, except we artificially fix the AMOC strength at preindustrial levels. With this design, we can formally attribute differences in climate change impacts between these two experiments to the AMOC decline. In addition, we quantify the state‐dependence of AMOC impacts by comparing the aforementioned experiments with a preindustrial simulation in which we artificially reduce the AMOC strength. Our findings demonstrate that AMOC decline impacts are state‐dependent, thus understanding AMOC impacts on future climate change requires targeted model experiments
Centennial-Scale Variability of the Atlantic Meridional Overturning Circulation in CMIP6 Models Shaped by Arctic–North Atlantic Interactions and Sea Ice Biases
No full textClimate variability on centennial timescales has often been linked to internal variability of the Atlantic Meridional Overturning Circulation (AMOC). However, due to the scarceness of suitable paleoclimate proxies and long climate model simulations, large uncertainties remain on the magnitude and physical mechanisms driving centennial-scale AMOC variability. For these reasons, we perform a systematic multi-model comparison of centennial-scale AMOC variability in pre-industrial control simulations of state-of-the-art global climate models. Six out of nine models in this study exhibit a statistically significant mode of centennial-scale AMOC variability. Our results show that freshwater exchanges between the Arctic Ocean and the North Atlantic provide a plausible driving mechanism in a subset of models, and that AMOC variability can be amplified by ocean–sea ice feedbacks in the Labrador Sea. The amplifying mechanism is linked to sea ice cover biases, which could provide an observational constraint for centennial-scale AMOC variability
Numerical modeling and experimental study of a box-section tube bundle thermal energy storage for free-cooling of buildings
No full textA numerical model able to simulate the thermal behavior of an energy storage made of a bundle of rectangular tubes is presented. This model take into account the close-contact melting phenomenon due to the decreasign density of the PCM as it melts. The numerical results are presented and discussed. Finally, an experimental study is performed to validate the modelling approach.Nobatek et FEDER Aquitain
High-latitude precipitation as a driver of multicentennial variability of the AMOC in a climate model of intermediate complexity
No full textCentennial-scale variability of the Atlantic Meridional Overturning Circulation (AMOC) in the absence of external forcing has been identified in several climate models, but proposed mechanisms differ considerably. Therefore, better understanding of processes governing AMOC variability at these timescales is needed. Here, we analyze numerical simulations with PlaSim-LSG, an Earth System Model Intermediate Complexity (EMIC), which exhibits strong multicentennial oscillations of AMOC strength under constant pre-industrial boundary conditions. We identify a novel mechanism in which these oscillations are driven by salinity anomalies from the Arctic Ocean, which can be attributed to changes in high-latitude precipitation. We further corroborate our findings by conducting a set of millennial-length sensitivity experiments, and we interpret the mechanism by formulating a three-box model which qualitatively reproduces regular oscillations of the AMOC. While PlaSim-LSG lacks complexity compared to state-of-the-art models, our results reveal that precipitation minus evaporation (P-E) change in the Arctic is a physically plausible driver of centennial-scale AMOC variability. We discuss how this mechanism might be most relevant in climate states warmer than the present-day, raising questions about the state-dependence of multicentennial AMOC variability
Interacción de ondas de choque débiles en agua con la materia: diseño de electrodos y reflectores novedosos para litotriptores electrohidráulicos
No full textLa presente tesis.es un estudio de la interaccién de las ondas de choque débiles en agua con la materia y su aplicacién a la medicina. La motivaci6én para dicho trabajo fue la aplicaci6én de estas ondas a la desintegraci6én de calculos sin cirugia (litotripsia extracorporal). A pesar de que esta técnica es un procedimiento de rutina en todo el mundo, existen atin muchas incégnitas al respecto. Como dispositivo experimental se us6 un generador disefiado y construido en el Instituto de Fisica de la UNAM. Convencionalmente las ondas de choque se generan por una descarga eléctrica entre dos electrodos colocados en uno de los dos focos (Fi) de un reflector metalico con forma de paraelipsoide de revolucién. Estas ondas, producidas por la expansidén del plasma entre los dos electrodos, colocados en el foco (Fi) mas cercano al reflector, se reflejan en las paredes del mismo y_ se concentran hacia el segundo foco (Fz) del elipsoide.. En el caso clinico se procura que el cdalculo quede situado en la vecindad del segundo foco. El objetivo principal de esta tesis fue el disefio y la construcci6én de electrodos y reflectores con caracteristicas novedosas para generar ondas de choque que permitan aumentar la eficiencia de los aparatos existentes hasta la fecha. Esto se logr6é cambiando la forma y el material de los electrodos asi como la geometria de los reflectores. Los nuevos reflectores ya no son simétricos respecto de un eje de revoluci6én, sino que estan formados por dos sectores de elipsoides de revolucién con pardmetros diferentes, unidos de tal manera que sus focos Fi coinciden. Esto genera un desfasamiento temporal y/o espacial de las ondas que llegan al calculo, pulverizandolo con un menor ntimero de ondas de choque generadas con la misma energia. Para evaluar la eficiencia de los dispositivos disefiados se expusieron cientos de modelos de calculos renales a las ondas de choque generadas con’ los sistemas convencionales y con los electrodos y reflectores nuevos.La presente tesis.es un estudio de la interacción de las ondas de choque débiles en agua con la materia y su aplicación a la medicina. La motivación para dicho trabajo fue la aplicación de eô€•tas ondas a la desintegración de cálculos sin cirugía (litotripsia extracorporal). A pesar de que esta técnica es un procedimiento de rutina en todo el mundo, existen aún muchas incógnitas al respecto. Como dispositivo experimental se usó un generador diseñado y construído en el Instituto de Física de la UNAM. Convencionalmente las ondas de choque se generan por una descarga eléctrica entre dos electrodos colocados en uno de los dos focos (F1) de un reflector metálico con forma de paraelipsoide de revolución. Estas ondas, producidas por la expansión del plasma entre los dos electrodos, colocados en el foco (F1) más cercano al reflector, se reflejan en las paredes del mismo y se concentran hacia el segundo foco (F2) del elipsoide .. En el caso clínico se procura que el cálculo quede situado en la vecindad del segundo foco. El objetivo principal de esta tesis fue el diseño y la construcción de electrodos y reflectores con características novedosas para generar ondas de choque que permitan aumentar la eficiencia de los aparatos existentes hasta la fecha. Esto se logró cambiando la forma y el material de los electrodos así como la geometría de los reflectores. Los nuevos reflectores ya no son simétricos respecto de un eje de revolución, sino que están formados por dos sectores de elipsoides de revolución con parámetros diferentes, unidos de tal manera que sus focos F1 coinciden. Esto genera un desfasamiento temporal y/o espacial de las ondas que llegan al cálculo, pulverizándolo con un menor número de ondas de choque generadas con la misma energía. Para evaluar la eficiencia de los dispositivos diseñados se expusieron cientos de modelos de cálculos renales a las ondas de choque generadas con' los sistemas convencionales y con los electrodos y reflectores nuevos
Integrated marketing communications strategy: An examination of Harrah’s Entertainment, Inc.
No full textThis professional paper is going to examine marketing communications, specifically the Integrated Marketing Communications (IMC) strategy. The paper will look at how to develop an IMC strategy, discussing the necessary components. The author will then apply Harrah’s current strategy of their Total Rewards program to the IMC model discussed in the literature review
Closing or opening the European Union: The debate on Turkish accession caught between kultur; civilisation and cosmopolitanism
No full textMehling, Sebastian (Dogus Author)This Essay is not meant to deliver a new history of Turkey-EU relations. Neither is it a fully-fledged discourse analysis of the debate on Turkish Accession within German Newspapers. Its focus lies instead on the political language, more precisely on the discursive logics, which were used within the discussion on the complex policy decision of whether or not Turkey can or should join the European Union. lts major claim is thereby, that it is the character of language that determines the way in which discussion about politics are structured. Language is accordingly defined, first, as a collectively derived 'tool-kit' which is only used by individuals. Every individual statement, indeed any individual reflection, is thus framed by collective structures and must obey predominant linguistic rules (to a certain extent) in order to be meaningful and enable the individual to communicate with its environment. On the other hand it is equally true, that .every meaningfu1 statement must redefine those structures, so as to adjust them and make them useful within the individual speech situation. What emerges from this perspective on language, is a mutual and tense relationship between structure and agency, between continuity and change and between the other and the self, i.e. a dialectical relationship between both, which is necessary to construct a meaningful reality. In consequence, and secondly, every meaningful statement must connect to a historicist beyond, i.e. an other time beyond the individual speech situation. The individual present must thus be embedded in speculations about past and future, in order to endow the statement made with the necessary element of consistency and direction in time, without however, proving that something like a meaningful history/futııre does exist outside of language. Thirdly, but equally emergıng from the first point, it is indispensable for every meaningful statement to refer to a collectivist beyond, i.e. the speculative and imagined other, which is not directly involved within the individual speech situation. This is done to endow the statement made with the necessary element of direction in (social) space, without, however, implying an authentic representation of the other within the statement made. Accordingly, every statement within a political debate cannot avoid potentially ideological speculations about a teleological connection of past and future, as well as it cannot avoid a stereo-typical representation and evaluation of difference, ranging from the same (or self), over similar ( or core ), to different ( or peripheral other) and contradictory ( or the outside other). On the other hand, however, it is exactly the actual utilisation of these linguistic tools within a communicative confrontation between two or more individual debate participants, which triggers a mutual re-definition of them and thus enables an inter-subjective creation of a social reality. Yet, this does not mean that communication leads necessarily to dialogue and understanding. It can equally lead to misunderstanding, or be performed through mutually exclusive monologues. Instead it means that all kinds of statements are formulated within a present negotiation and bargaining process, in which commonsensical knowledge about the self and the other, about the past and the future, is re-defined according to the new situation at hand. It is thus feasible to approach the complex discursive landscape of the debate on Turkish accession to the EU, from the perspective of language. If one does so it becomes clear how the specific argumentation used connect to certain discursive logics, so as to receive from them the necessary normative horizon it needs to produce itself as authentic reflection on reality, which can trigger consistent and morally legitimate decisions. The structuring discourse logics used within the debate, can be categorised under the labels of the French notion of Civilisation, the German notion of Kultur, and the English notion of cosmopolitanism. This categorisation thereby is constructed as ideal-type categorisation, which reduces an over-complex debate reality and creates clear-cut distinctions between the camps, in order to provide a structure that can trigger understanding. However, it does not suggest that the ideal types formulated strictly correspond to anything real. lt thus resembles both, the structuring frame of language and the ideological and stereotypical distortions, which necessarily emerge from this reductionist, selective and speculative procedure of structuring. The ideal types of Civilisation, Kultur and cosmopolitanism are accordingly defined as discursive logics, which produce mutually exclusive but interdependent, ideological evaluations of historical and social development. Yet, although these evaluations do not correspond to any social reality, they are nevertheless able to re-create it through their employment of a self-referential and self-evident, i.e. quasi-realistic narrative, which sets itself off against the other logics and thus produces itself as the more realistic and more trustful alternative. Hence, by doing this, the discursive logics employ the linguistic fundamental of a dialectical relation between two poles (thesis and antithesis), whereby reality logically must emerge in between those poles (as a synthesis). An argumentative chain based on the logic of Civilisation, for example, can thus materialize itself as more realistic, when it is able to disqualify counterarguments as being based on the ' amoral ', 'unrealistic' and 'obsolete' boundaries of a thesis Kultur and antithesis cosmopolitanism, which are accordingly synthesised and balanced within the logic of Civilisation. However, this process works as well from out the other discursive logics, exactly because neither of them can be verifıed or falsified, i.e. objectively proven by the yardstick of an outside reality. Instead, they produce reality among each other verify themselves by falsifying the altematives, within a mutual but tense relationship of dependence and exclusion. Accordingly one can define the three discursive logics as fundamentally based on the same linguistic method of dialectical production of reality, whereby, they however, essentially differ in the way they emphasis on one feature of society and de-emphasise the corresponding alternatives. Whether one or the other discursive logic is used does therefore not depend on their objectivity, but instead on their utility for the identity project of the debate participant that employs one of them. The analysis of (a selection of articles from) the German debate illustrates this fact by applying the theoretically derived ideal-type categorisation to newspaper articles, which were published in between 2002 and 2004. The statements made in those articles are all essentially based on normative speculations about what the specific qualities of European societies are. In so doing they derive their meaning not primarily from their analytical quality. Their meaning rather depends on their capacity to construct an internally consistent narrative, i.e. their ability to re-produce the framing discourse logics of Civilisation, Kultur or cosmopolitanism and to establish an ordering hierarchy among them within the speech situation at hand. The thesis concludes thus that it is impossible to arrive at an objectively right evaluation of the compiex social environment around the political decision whether Turkey should join the EU or not. However, the more channels for communication exist, where individuals can confront and (re-)negotiate their commonsensical knowledge with or against each other, the more probable it is that a dynamic debate emerges, which keeps the fruitful dialectical tension alive. The question, whether an entity called Turkey will join a European Union or not, is thus not so important. More important is the question how one can intensify the communicative engagement between individuals of both, the societies of the EU Member States and the Turkish society.PREFACE, IV -- SUMMARY, V -- INTR0DUCTION: THE NEVER ENDING STORIES OF TURKEY AND THE EU, 8 -- 1. The fortresses of Europe or the monasteries of Europe? - European Kultur vs. -- European Civilisation vs. European Cosmopolitanism, 14 -- 1.1. Civilisation and Orientalism - Revolutionary Enlightenment and the civilised European Empire, 27 -- 1.2. Kultur & Occidentalism - Conservative Romanticism and the World of (German) Nations, 34 -- 1.3. Cosmpolitanism - Liberal Enlightenment and Reflective Individualism as the cure for a plagued Continent, 42 -- 2. Closing or opening up the European Union? - The debate on Turkish Accession -- caught between Kultur and Civilisation - and what about Cosmopolitanism?, 51 -- 2.1. Discursive construction of the other, 53 -- 2.2. The debate in German Newspapers, 64 -- Conclusion, 92 -- 4. Annex, 100 -- 4.1. Hans Ulrich Wehler; Die türkische Frage. Europas Bürger müssen entscheiden, 100 -- 4.2. Seyla Benhabib; Das türkische Mosaik. Ein lrrtum zu meinen, Europa müsse am Bosporus enden, 108 -- 4.3. Cristian Meier: Wo liegt Europa? Historische Reflexionen - aus gegebenem.Anlass, 112 -- 4.4. Kardinal Josef Ratzinger; Auf der Suche nach dem Frieden. Gegen erkrankte Vernunft und missbrauchte Religion, 118 -- 4.5. Armin Adam; Der ideelle Kern. Lasst sich eine Vorstellung von Europa gewinnen, die seine religiöse Geschiche nicht verfalscht?, 124 -- 4.6. Heinz Kramer; EU-kompatible oder nicht? Zur Debatte um die Mitgliedschaft der Türkei in der Europaischen Union. Berlin: SWP Studie, 128 -- 5. Biblography, 1
Die Ludloff Osteotomie zur Verlängerung des Ersten Strahles mit Arthrodese des Großzehengundgelenkes bei Spätkomplikation nach Keller-Brandes Operation
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