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1
Karlsson, Johan, and Andreas Ljung. "Bors E23 - Framtagning av eldriven röravklippningsmaskin." Thesis, Halmstad University, School of Business and Engineering (SET), 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-943.
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Our Bachelor´s Thesis has been performed in co-operation with Bors Automation & Tool AB.
Our task was to develop a servomotor powered tube cutting-machine with initial point from
today's hydraulic driven tube cutting machine Bors HYD 23. The purpose with the new
construction was to achieve a more power-efficient tube cutting machine which could lower
the power consumption, and also meet the market continued growing demand for
environmental-conscious production.
Bors Automation & Tool gave us relatively free hands in order to enable new thinking ideas
without following their traditional constructional solutions.
Our solution resulted in a construction based on a power source existing of a servomotordriven
rollerscrew, witch provides a more rational use of energy compared with the current
method.
Bors Automation & Tool AB has decided to fabricate a prototype of Bors E 23 during the
autumn of 2007, which they are planning to revile at the Tube 2008 exhibition in Düsseldorf,
Germany.
NOTE:
Due to an agreement signed by the authors in the beginning of this project, no appendix is published at this time.
If you want to wiew these documents, please contact the authors.
2
Punzi, Maria Teresa, and Katrin Rabitsch. "Effectiveness of macroprudential policies under borrower heterogeneity." WU Vienna University of Economics and Business, 2017. http://epub.wu.ac.at/5731/1/wp253.pdf.
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We study the impact of macroprudential policies using a novel model which takes into account households´ ability to borrow under different loan-to-value ratios which are tied to their collateral values. Such model generates a larger
amplification in real and financial variables, compared to standard models that assume homogeneity in the leveraging and deleveraging process. Conditional on this model, we consider the implications of macroprudential policies that aim to lean against an excessive credit cycle. In particular, we allow macroprudential authorities to tighten excessive lending to higher leveraged households, whose riskiness had been evaluated too optimistically. We find thata policy that targets only the group of households that most strongly deleveraged after an adverse idiosyncratic housing investment risk shock, is welfare-improving
at social and individual levels, relative to a macroprudential policy which targets all households in the economy.Series: Department of Economics Working Paper Series
3
Huber, Florian, and Maria Teresa Punzi. "The shortage of safe assets in the US investment portfolio: Some international evidence." WU Vienna University of Economics and Business, 2017. http://epub.wu.ac.at/5460/1/wp243.pdf.
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This paper develops a Bayesian Global VAR (GVAR) model to track the international transmission dynamics of two stylized shocks, namely a supply and demand shock to US-based safe assets. Our main findings can be summarized as follows. First, we find that (positive) supply-sided shocks lead to pronounced increases in economic activity which spills over to foreign countries. The impact of supply-sided shocks can also be seen for other quantities of interest, most notably equity prices and exchange rates in Europe. Second, a demand-sided shock leads to an appreciation of the US dollar and generally lower yields on US securities, forcing investors to shift their portfolios towards foreign fixed income securities. This yields sizable positive effects on US output, equity prices and a general decrease in financial market volatility.Series: Department of Economics Working Paper Series
4
Rabitsch, Katrin, and Maria Teresa Punzi. "Borrower heterogeneity within a risky mortgage-lending market." WU Vienna University of Economics and Business, 2017. http://epub.wu.ac.at/5429/1/wp241.pdf.
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We propose a model of a risky mortgage-lending market in which we take explicit account of heterogeneity in household borrowing conditions, by introducing two borrower types: one with a low loan-to-value (LTV) ratio, one with a high LTV ratio, calibrated to U.S. data. We use such framework to study a deleveraging shock, modeled as an increase in housing investment risk, that falls more strongly on, and produces a larger contraction in credit for high-LTV type borrowers, as in the data. We find that this deleveraging experience produces significant aggregate effects on output and consumption, and that the contractionary effects are orders of magnitudes higher in a model version that takes account of borrower heterogeneity, compared to a more standard model version with a representative borrower.Series: Department of Economics Working Paper Series
5
Huber, Florian, and Maria Teresa Punzi. "International Housing Markets, Unconventional Monetary Policy and the Zero Lower Bound." WU Vienna University of Economics and Business, 2016. http://epub.wu.ac.at/4824/1/wp216.pdf.
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In this paper we propose a time-varying parameter VAR model for the housing market in the United States, the United Kingdom, Japan and the Euro Area. For these four economies, we answer the following research questions: (i) How can we evaluate the stance of monetary policy when the policy rate hits the zero lower bound? (ii) Can developments in the housing market still be explained by policy measures adopted by central banks? (iii) Did central banks succeed in mitigating the detrimental impact of the financial crisis on selected housing variables? We analyze the relationship between unconventional monetary policy and the housing markets by using the shadow interest rate estimated by Krippner (2013b). Our findings suggest that the monetary policy transmission mechanism to the housing market has not changed with the implementation of quantitative easing or forward guidance, and central banks can affect the composition of an investors portfolio through investment in housing. A counterfactual exercise provides some evidence that unconventional monetary policy has been particularly successful in dampening the consequences of the financial crisis on housing markets in the United States, while the effects are more muted in the other countries considered in this study. (authors' abstract)Series: Department of Economics Working Paper Series
6
Naqvi, Syed Ali Asjad. "Modeling Growth, Distribution, and the Environment in a Stock-Flow Consistent Framework." WU Vienna University of Economics and Business, 2015. http://epub.wu.ac.at/4468/1/EcolEcon_WorkingPaper_2015_2.pdf.
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Economic policy in the EU faces a trilemma of solving three challenges simultaneously - growth, distribution, and the environment. In order to assess policies that address these
issues simultaneously, economic models need to account for both sector-sector and sector-environment feedbacks within a single framework.This paper presents a multi-sectoral stock-flow consistent (SFC) macro model where a demand-driven economy consisting of multiple institutional sectors - firms, energy, households, government, and financial - interacts with the environment. The model is calibrated for the EU region and five policy scenarios are evaluated; low consumption, a capital stock damage function, carbon taxes, higher share of renewable energy, and technological shocks to productivity. Policy outcomes are tracked on overall output, unemployment, income and income distributions, energy, and emission levels. Results show that investment in mitigation technologies allows for absolute decoupling and ensures that the above three issues can be solved simultaneously. (author's abstract)Series: Ecological Economic Papers
7
Naqvi, Asjad. "Modeling Growth, Distribution, and the Environment in a Stock-Flow Consistent Framework. Policy Paper no 18." European Commission, bmwfw, 2015. http://epub.wu.ac.at/4736/1/WWWforEurope_Policy_Paper_018.pdf.
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Economic policy in the EU faces a trilemma of solving three challenges simultaneously - growth, distribution, and the environment. In order to assess policies that address these issues simultaneously, economic models need to account for both sector-sector and sector-environment feedbacks within a single framework.This paper presents a multi-sectoral stock-flow consistent (SFC) macro model where a demand-driven economy consisting of multiple institutional sectors - firms, energy, households, government, and financial - interacts with the environment. The model is calibrated for the EU region and five policy scenarios are evaluated; low consumption, a capital stock damage function, carbon taxes, higher share of renewable energy, and technological shocks to productivity. Policy outcomes are tracked on overall output, unemployment, income and income distributions, energy, and emission levels. Results show that investment in mitigation technologies allows for absolute decoupling and ensures that the above three issues can be solved simultaneously.Series: WWWforEurope
8
Rengs, Bernhard, and Manuel Scholz-Wäckerle. "Consumption & class in evolutionary macroeconomics." Springer Berlin Heidelberg, 2018. http://dx.doi.org/10.1007/s00191-018-0592-2.
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This article contributes to the field of evolutionary macroeconomics by
highlighting the dynamic interlinkages between micro-meso-macro with a Veblenian
meso foundation in an agent-based macroeconomic model. Consumption
is dependent on endogenously changing social class and signaling, such as
bandwagon, Veblen and snob effects. In particular, we test the macroeconomic
effects of this meso foundation in a generic agent-based model of a closed
artificial economy. The model is stock-flow consistent and builds upon local
decision heuristics of heterogeneous agents characterized by bounded rationality
and satisficing behavior. These agents include a multitude of households
(workers and capitalists), firms, banks as well as a capital goods firm, a
government and a central bank. Simulation experiments indicate coevolutionary
dynamics between signaling-by-consuming and firm specialization
that eventually effect employment and consumer prices, as well as other
macroeconomic aggregates.
9
Hein, Eckhard. "Shareholder value orientation, distribution and growth - short- and medium-run effects in a Kaleckian model." Inst. für Volkswirtschaftstheorie und -politik, WU Vienna University of Economics and Business, 2008. http://epub.wu.ac.at/930/1/document.pdf.
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We discuss the effects of rising shareholder power on distribution and capital accumulation in a Kaleckian model. Increasing shareholder power is associated with decreasing managements' animal spirits, on the one hand, and increasing dividends distributed to shareholders, on the other hand. In the short run, increasing shareholder power may either have positive ('finance-led'), negative ('normal') or intermediate ('profits without investment') effects on capacity utilisation, profits and capital accumulation. In the medium run, the positive ('finance-led') effects may be maintained in a stable environment under very special conditions, whereas the negative ('normal') and the intermediate ('profits without investment') effects turn into cumulative disequilibrium processes with falling rates of capacity utilisation, profits and capital accumulation and rising debt- and rentiers' equity-capital-ratios. (author´s abstract)Series: Department of Economics Working Paper Series
10
Stockhammer, Engelbert, Özlem Onaran, and Stefan Ederer. "Functional income distribution and aggregate demand in the Euro-area." Inst. für Volkswirtschaftstheorie und -politik, WU Vienna University of Economics and Business, 2007. http://epub.wu.ac.at/346/1/document.pdf.
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An increase in the wage share has contradictory effects on the subaggregates of aggregate demand. Private consumption expenditures ought to increase because wage incomes typically are associated with higher consumption propensities than capital incomes. Investment expenditures ought to be negatively affected because investment will positively depend on profits. Net exports will be negatively affected because an increase in the wage share corresponds to an increase in unit labor costs and thus a loss in competitiveness. Theoretically aggregate demand can therefore be either wage led or profit led depending on how these effects add up. The results will crucially depend on how open the economy is internationally. The paper estimates a Post-Kaleckian macro model incorporating these effects for the Euro area and finds that the Euro area is presently in a wage-led demand regime. Implications for wage policies are discussed. (author's abstract)Series: Department of Economics Working Paper Series
11
Stockhammer, Engelbert, and Stefan Ederer. "Demand effects of the falling wage share in Austria." Inst. für Volkswirtschaftstheorie und -politik, WU Vienna University of Economics and Business, 2007. http://epub.wu.ac.at/1020/1/document.pdf.
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This paper aims at empirically estimating the demand effects of changes in functional income distribution for Austria. Based on a Post-Kaleckian macro model, this paper estimates the effects of a change in the wage share on the main demand aggregates. The results for the behavioral functions for consumption, investment, prices, exports and imports are compared with the specifications of the WIFO macro model and the IHS macro model. A reduction in the wage share has a restrictive effect on domestic demand as consumption decreases more strongly than investment increases. Because of the strong effects on net exports the overall effects of a decrease in the wage share are expansionary. However the latter effect operates only as far as the fall in the wage share increases competitiveness. As wage shares were also falling in Austria's main trading partners, the effect seems to have been neutralized. (author's abstract)Series: Department of Economics Working Paper Series
12
Stockhammer, Engelbert, Eckhard Hein, and Lucas Grafl. "Globalization and the effects of changes in functional income distribution on aggregate demand in Germany." Inst. für Volkswirtschaftstheorie und -politik, WU Vienna University of Economics and Business, 2007. http://epub.wu.ac.at/1104/1/document.pdf.
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Germany has experienced a period of extreme nominal and real wage moderation since the mid 1990s. Contrary to the expectations of liberal economists this has failed to improve Germany's mediocre economic performance. However, Germany is now running substantial current account surpluses. One possible explanation for Germany's disappointing performance is found in Kaleckian theory, which highlights that the domestic demand effect of a decline in the wage share will typically be contractionary, whereas net exports will increase (Blecker 1989). The size of the foreign demand effect will critically depend on the degree of openness of the economy. The paper aims at estimating the demand side of a Bhaduri-Marglin (1990) -type model empirically for Germany. The paper builds on the estimation strategy of Stockhammer, Onaran and Ederer (2007) and Hein and Vogel (2008a, 2008b). The main contribution lies in a careful analysis of the effects of globalization. Since Germany is a large open economy by now it is a particularly interesting case study. (author´s abstract)Series: Department of Economics Working Paper Series
13
Stockhammer, Engelbert, and Lucas Grafl. "Financial uncertainty and business investment." Inst. für Volkswirtschaftstheorie und -politik, WU Vienna University of Economics and Business, 2008. http://epub.wu.ac.at/564/1/document.pdf.
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The paper seeks to contribute to the empirical analysis of financial uncertainty and investment from a Post Keynesian perspective. The paper uses the volatility of the exchange rate, the volatility of the stock market index, and the real gold price as indicators for financial uncertainty. An increase in the volatility of a variable is a sufficient, but not a necessary condition for an increase in uncertainty (regarding this variable). The effects of changes in uncertainty on investment are investigated econometrically for the USA, the UK, the Netherlands, Germany, and France. Financial uncertainty has significant negative effects in the USA and the Netherlands. (author´s abstract)Series: Department of Economics Working Paper Series
14
Schreiber, Caroline. "Identifizierung neuer E2F-Zielgene in der Wachstumskontrolle und Tumorprogression." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2008. http://dx.doi.org/10.18452/15849.
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Der pRB/E2F-Signalweg ist ein wichtiger Schlüsselpunkt für die Wachstumskontrolle in Säugerzellen und in vielen Tumoren sind Komponenten dieses Signalweges dereguliert. Durch die Nullmutation von E2F3 in Mausembryonalen Fibroblasten (MEFs) und Mäusen konnte gezeigt werden, dass E2F3 essentiell für das zelluläre Wachstum ist und in der Maus organspezifisch sowohl als Tumorsuppressor als auch Onkogen agieren kann. Jedoch sind dafür die zugrunde liegenden Mechanismen noch nicht genau geklärt. Möglicherweise tragen verschiedene Signalwege, die durch den Verlust von E2F3 dereguliert werden, zu den Defekten bei. In dieser Arbeit wurde TGFbeta1, ein wichtiger Wachstumsregulator, in den E2f3-/- MEFs untersucht und es konnte zum ersten Mal eine direkte Verbindung zwischen der E2F3-Expression und der TGFbeta1-Signalwirkung gezeigt werden. Durch den Verlust von E2F3 werden Tgfb1 und die TGFbeta1-regulierten Gene PAI-1, p21, Vimentin und Fibronectin in MEFs dereprimiert. Darüber hinaus werden MEFs und humane Lungenkarzinomzellen durch den Verlust von E2F3 gegenüber TGFbeta1 sensibilisiert und reagieren verstärkt auf TGFbeta1-induzierte Genexpression und Prozesse wie Wachstumsarrest und EMT. Somit wird E2F3 nicht nur durch TGFbeta1 reguliert, sondern kann auch auf TGFbeta1 und die TGFbeta1-Signalwirkung Einfluss nehmen, was für die Tumorprogression weit reichende Auswirkung haben kann. Um die tumorsuppressiven Eigenschaften von E2F3 besser zu verstehen, wurden im zweiten Teil dieser Arbeit murine medulläre Schilddrüsentumore mit unterschiedlichem metastatischen Potential miteinander verglichen und es konnten neue E2F-Zielgene identifiziert werden. Die Untersuchung von humanen Struma nodosa-Biopsien und metastatischen medullären Schilddrüsentumoren ergab, dass die in den Mäusen gefundenen Gene künftig auch als humane Metastasemarker Verwendung finden können.The pRB/E2F-pathway plays a key role in growth control and it is deregulated in many tumors. Previously, by analysing E2f3 deficient mouse embryonic fibroblasts (MEFs) and mice it has been shown that E2F3, a key downstream target of pRB, is essential for cellular proliferation and can act either as an oncogene or tumorsuppressor in mice depending on the organ. However, the underlying mechanism is still unclear. We suggest that specific pathways which are deregulated due to the deletion of E2F3 contribute to these defects. TGFbeta1, which is one of the most potent growth regulators for mammalian cells was analysed in E2f3-/- MEFs. In this study, we could establish a direct link between E2F3 expression and TGFbeta1 signalling. Loss of E2F3 in MEFs leads to de-repression of Tgfb1 and TGFbeta1-regulated genes like PAI-1, p21, vimentin and fibronectin. Moreover, loss of E2F3 in MEFs or in human lung carcinoma cells results in an increased sensitivity to TGFbeta1-induced gene expression and processes like growth arrest and epithelial mesenchymal transition. These data suggest that not only TGFbeta1 can act on E2F3 but also E2F3 can affect TGFbeta1 and the outcome of TGFbeta1-induced signalling. In order to understand the tumor suppressive properties of E2F3, we compared gene expression profiles of murine medullary thyroid carcinomas (MTCs) of different metastatic potential and could identify novel E2F-target genes. Analysis of human struma nodosa biopsies and human metastatic medullary thyroid tumors showed that the genes identified in the mouse model can also be used as metastasis markers in human tumors.
15
Ederer, Stefan, and Miriam Rehm. "Wealth inequality and aggregate demand." WU Vienna University of Economics and Business, 2019. http://epub.wu.ac.at/7171/1/WP_30.pdf.
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The paper investigates how including the distribution of wealth changes the demand effects of redistributing functional income. It develops a model with an endogenous wealth distribution and shows that the endogenous rise in wealth inequality resulting from a redistribution towards profits weakens the growth effects of this redistribution. Consequently, a wage-led regime becomes more strongly wage-led. A profit-led regime on the other hand becomes less profit-led and there may even be a regime switch - in this case the short-run profit-led economy becomes wage-led in the long run due to the endogenous effects of wealth inequality. The paper thereby provides a possible explanation for the instability of demand regimes over time.Series: Ecological Economic Papers
16
Garcia-Hernandez, Margarita. "Systèmes luminescents BaTiO3 : Ln(Ln= Er3+, Yb3+, Eu3+) préparés par chimie douce : poudres, nanopoudres et films nanostructurés." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2010. http://tel.archives-ouvertes.fr/tel-00719196.
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Ce travail concerne, la synthèse, la caractérisation structurale, morphologique et optique de matrices de titanates de baryum (BaTiO3) activées par les ions Eu3+, Er3+ et Yb3+. Trois voies de synthèse sont étudiées : sol-gel, hydrothermale et solide. Il a été montré que la synthèse hydrothermale conduisait à des poudres nanométriques constituées de particules de 20 nm, dix fois plus petites que celles rencontrées dans les poudres obtenues par les techniques classiques de céramisation. L' influence de ce paramètre sur la structure cristallographique des titanates a pu être mise en évidence. L'ajout d'agents chélatants au cours de la synthèse sol-gel permet de modifier la morphologie des poudres et de stabiliser les sols destinés à l'élaboration de revêtements. Des films épais monocouche ( 800 nm) de titanates de baryum dopés Er3+ et Eu3+ ont été ainsi obtenus. Une étude des propriétés optiques des ions de terres rares dans les différents systèmes synthétisés a été menée en enregistrant les différents spectres d'exitation et d'émission. Les phénomènes de transfert d'énergie entre les ions de terres rares ont été étudiés dans les matrices co-dopées
17
LIMA, Bismarck Costa. "Estudo da conversão descendente de frequência com íons de Tb3+/Yb3+ , Eu3+ e Er3+ para aplicações fotovoltaicas." Universidade Federal de Pernambuco, 2015. https://repositorio.ufpe.br/handle/123456789/16118.
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CAPES, CNPq, FACEPE
C elulas solares apresentam-se como uma alternativa vi avel para a gera c~ao de energia limpa e renov avel pela sua capacidade de convers~ao da energia solar em el etrica atrav es do efeito fotovoltaico. Entretanto, um dos fatores limitantes na utiliza c~ao deste tipo de energia tem sido a incompatibilidade espectral, a qual implica que apenas uma determinada parte do espectro solar seja efetivamente utilizado no processo de convers~ao fotovoltaica. Entre os diversos materiais fot^onicos, pesquisas em materiais dopados com ons de Terras Raras capazes de realizar a convers~ao de f otons de infravermelho para vis vel-UV ou vice-versa tem sido realizadas. Em aplica c~oes fotovoltaicas, este efeito pode melhorar a coleta da radia c~ao solar. Para a realiza c~ao desta tarefa dois mecanismos s~ao utilizados: Convers~ao Ascendente de Frequ^encia e Convers~ao Descendente de Frequ^encia. Este trabalho teve como objetivo estudar as propriedades espectrosc opicas e o mecanismo de Convers~ao Descendente de Frequ^encia em vidros dopados com os ons de Terras Raras Tb3+/Yb3+, Eu3+ e Er3+, e veri car suas poss veis aplica c~oes no melhoramento da e ci^encia de c elulas solares. A mesma matriz hospedeira foi utilizada. O estudo das propriedades espectrosc opicas foi realizado atrav es de medidas de absor c~ao, luminesc^encia e evolu c~ao temporal da luminesc^encia. Observamos o processo de convers~ao descendente de frequ^encia com emiss~ao no infravermelho, regi~ao que as c elulas solares de sil cio cristalino possuem maior e ci^encia, com excita c~ao em 355nm, que promoveu uma maior e ci^encia, e 482nm. Em seguida, para as matrizes dopadas com ons de Tb3+/Yb3+, foi determinado o mecanismo gerador do processo de convers~ao descendente de frequ^encia e a e ci^encia de transfer^encia de energia. Foi obtida uma e ci^encia de transfer^ encia de energia m axima de 112,7%. Para as matrizes dopadas com Eu3+ e Er3+ foram realizadas medidas de luminesc^encia com excita c~ao via laser de 482nm. Como aplica c~ao, foram realizadas medidas el etricas, para c elulas convencionais de Si e GaP, usando como fonte de radia c~ao um simulador solar com ltro AM 1.5. Os resultados foram avaliadas na presen ca e aus^encia dos vidros dopados com ons de Terras Raras na superf cie da c elula solar. Foi observado um aumento na e ci^encia de convers~ao fotovoltaica das c elulas de sil cio cobertas pelos vidros dopadas com 1%Tb3+ e 1%Eu3+ em rela c~ao a matriz sem dopagem.
Solar cells are shown as a viable alternative for generation renewable and clean energy due their ability of converter solar power in electric power by the photovoltaic e ect. However, one of the limitant facts to use photovoltaic devices to make electricity is spectral mismatch, that implies only a speci c range of solar spectrum is e ectively used in the process of photovoltaic conversion. Between the several photonics devices, research in Rare Earth ions doped materials able to do the conversion of infrared photons in visible-UV photons or the opposite have been performed. In photovoltaic applications, this e ect can enhance the harvesting of solar light. To realize this task two mechanism are used: Frequency up-conversion and frequency down-conversion. This work had the goal of study the spectroscopic properties and the Frequency Down-conversion mechanism in Tb3+/Yb3+, Eu3+ and Er3+ Rare Earth doped glasses, and check their possible applications to enhance solar cell e ciency. The same host matrix are used. The spectroscopic study was realized by luminescence, absorption, and temporal evolution luminescence measurements. We observe the frequency down-conversion and infrared emission, zone that crystaline silicon solar cell have the best e ciency, with 355nm excitation, that promote the best e ciency, and 482nm excitation. Then, for host matrix doped with Tb3+/Yb3+ ions, was determined the generation mechanism of frequency down-conversion and energy transfer e ciency. The major energy transfer e ciency was 112,7%. For host matriz doped with Eu3+ and Er3+ ions, was realized luminescence measurements with 482nm excitaion. Was realized electric measurements as applications in Si and GaP cells, solar simulator with AM 1.5 lter was used as radiation source. The results were evaluated with and without Rare Earth ions doped glasses on the surface of solar cell. We observed the enhancement of photovoltaic conversion when the silicon solar cell are covered with by glasses doped with 1%Tb3+ and 1%Eu3+ with respect to matrix covered.
18
Halambalakis, Georgios. "Optical and structural properties of Tm3+, Eu3+ and Er3+ doped GaN thin films grown by MBE technology." Montpellier 2, 2005. http://www.theses.fr/2005MON20045.
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Les propriétés optiques des couches épitaxiées de GaN dopées aux terres rares ont attiré l'attention pour des applications optoélectroniques tels que la signalisation, [la] lumière blanche et [les] communications optiques. Nous avons étudié les propriétés optiques et structurales des couches minces de GaN dopées aux terres rares (Er3+, Eu3+, Tm3+), réalisées par GSMBE (Gas Source Molecular Beam Epitaxy). La totalité du spectre de la lumière visible a été observé, du GaN:Eu (Rouge : 622 nm) au GaN:Tm (Bleu : 477 nm), en passant par le GaN:Er (Vert : 537 nm, 558 nm). La diffraction de rayons X a été utilisée pour étudier la qualité cristalline des couches. La microscopie électronique en transmission (TEM) a été utilisée pour étudier les défauts dus à l'incorporation d'ions de terres rares dans la matrice de GaN. Des mesures AFM ont aussi été utilisées pour étudier les effets de la température de croissance et de la concentration de terres rares sur la morphologie de la surface des couches dopées. Les études structurales sur les couches de GaN dopées aux terres rares ont montré que les défauts participent au mécanisme de transfert d'énergie de la matrice vers les ions de terres rares, ce qui accroît l'émission de lumière relative aux transitions intra-4f des terres rares, observées par photoluminescence.
19
Crespo, Cuaresma Jesus, and Octavio Fernandez-Amador. "Business cycle convergence in EMU: A first look at the second moment." Elsevier, 2013. http://epub.wu.ac.at/4128/1/JIMF_TP.pdf.
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We analyse the dynamics of the standard deviation of demand and supply shocks as
well as of the demand component of GDP across countries in the European Monetary
Union (EMU). This analysis allows us to evaluate the patterns of cyclical comovement
in EMU and compare them the cyclical performance of the new members of the EU
and other OECD countries. We make use of sigma-convergence methods to identify
synchronization patterns in business cycles. The Eurozone has converged to a stable
lower level of dispersion across business cycles during the end of the 80s and the beginning
of the 90s. The new EU members have also experienced a strong pattern of
convergence from 1998 to 2005, when a strong divergence trend appears. An enlargement
of the EMU to 22 members would not significantly decrease its optimality as a
currency area. There is evidence for some Europe-specific characteristics as compared
to global comovements in business cycles. (authors' abstract)
20
Garcia-Hernandez, Margarita. "Luminescent systems of Ln (Ln=Er3+, Yb3+ , Eu3+) doped BaTiO3 nanostructured powders and films prepared by soft chemical routes." Clermont-Ferrand 2, 2010. http://www.theses.fr/2010CLF22040.
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Ce travail concerne, la synthèse, la caractérisation structurale, morphologique et optique de matrices de titanates de baryum (BaTiO3) activées par les ions Eu3+, Er3+ et Yb3+. Trois voies de synthèse sont étudiées : sol-gel, hydrothermale et solide. Il a été montré que la synthèse hydrothermale conduisait à des poudres nanométriques constituées de particules de 20 nm, dix fois plus petites que celles rencontrées dans les poudres obtenues par les techniques classiques de céramisation. L' influence de ce paramètre sur la structure cristallographique des titanates a pu être mise en évidence. L'ajout d'agents chélatants au cours de la synthèse sol-gel permet de modifier la morphologie des poudres et de stabiliser les sols destinés à l'élaboration de revêtements. Des films épais monocouche ( 800 nm) de titanates de baryum dopés Er3+ et Eu3+ ont été ainsi obtenus. Une étude des propriétés optiques des ions de terres rares dans les différents systèmes synthétisés a été menée en enregistrant les différents spectres d'exitation et d'émission. Les phénomènes de transfert d'énergie entre les ions de terres rares ont été étudiés dans les matrices co-dopées
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Hassouneh, Ramzi. "Prostaglandin E2 Receptor 3 (EP3) Contributes to Polyuria, Glomerular Hyperfiltration, and Renal Injury in Diabetes." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32773.
Full textAbstract:
Cyclooxygenases (COXs) and their main renal product, prostaglandin E2 (PGE2), regulate many physiological renal functions and are involved in the pathogenesis of diabetic kidney disease. The PGE2 receptor EP3 has been repeatedly shown to be upregulated during diabetes. Physiologically, EP3 is best recognized to act as a diuretic by antagonizing arginine-vasopressin (AVP)-mediated water reabsorption. Incidentally, the first renal manifestation of diabetes is polyuria, which may trigger a cascade of events leading to DN. We hypothesize that EP3 contributes to polyuria and kidney dysfunction during diabetes. We injected EP3-/- mice with streptozotocin (STZ) and evaluated their renal function 12-weeks post injection. EP3-/- STZ mice exhibit attenuated polyuria while exhibiting increased urine osmolality suggesting enhanced water reabsorption. Western blots reveal that EP3-/- STZ mice have increased expression of aquaporin-1 and aquaporin-2 as well as reduced urinary AVP excretion compared to STZ mice. However, salt transporters were equivalently increased in STZ and EP3-/- STZ mice. In vitro microperfusion shows that EP3 completely abrogates AVP-mediated water reabsorption in STZ cortical collecting ducts. Furthermore, EP3-/- STZ mice showed blunted renal COX-2 expression as well as reduced renal hypertrophy, glomerular hyperfiltration, and albuminuria. Taken together, the data suggests that EP3 contributes to polyuria during diabetes by inhibiting expression of aquaporins. Additionally, EP3 seems to contribute to renal COX-2 induction during diabetes. The lack of an increase in renal COX-2 protein levels in EP3-/- STZ mice may be protective by preventing further renal damage.
22
Bodiou, Loic. "Etude des mécanismes d'excitation et d'émission de couches minces de GaN dopées Eu3+, Er3+ et Tm3+ pour nouveaux dispositifs électroluminescents." Phd thesis, Université de Caen, 2007. http://tel.archives-ouvertes.fr/tel-00324656.
Full textAbstract:
Cette thèse porte sur les mécanismes d'excitation et d'émission des couches minces de nitrure de gallium dopées par des ions de terre rare (Eu3+, Er3+ et Tm3+) suite à une excitation optique (photoluminescence) ou électrique (électroluminescence) du matériau semi-conducteur.A l'intérieur du GaN, deux catégories de site d'incorporation d'ions de terre rare peuvent être distinguées, à savoir les ions de terre rare "isolés" (c'est-à-dire ne contenant aucun défaut dans leur voisinage) et les complexes associant un ion de terre rare avec un piège, celui-ci pouvant provenir du dopage lui-même ou d'un défaut cristallin. L'excitation non-résonante est réservée au second type de centres et a lieu par transfert d'énergie lors de la recombinaison non radiative d'un exciton lié sur un piège proche de la terre rare.
La comparaison d'échantillons de GaN dopés in situ et par implantation ionique par l'ion Eu3+ montre que ces films présentent chacun deux types de complexes "Eu3+-piège" dont l'un est commun à tous les échantillons. Les différences d'efficacité d'excitation respectives des deux complexes s'expliquent par la proximité du piège correspondant.
Grâce à des expériences pompe-sonde combinant des lasers impulsionnel et continu, le chemin d'excitation des ions de terre rare est confirmé expérimentalement et deux des mécanismes d'extinction de leur luminescence (la photo-ionisation de pièges et l'effet Auger avec des porteurs libres) sont étudiés.
L'excitation électrique du GaN:Er3+ est également présentée. Les études en fonction de la température, du courant parcourant l'échantillon ou de la tension de polarisation mettent en évidence l'excitation par impact des ions de terre rare.
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Bahtat, Abdelhalim. "Elaboration et étude spectroscopique de couches minces de TiO2 optiquement guidantes : rôle du dopage par les ions Eu3+ et Er3+." Lyon 1, 1996. http://www.theses.fr/1996LYO10013.
Full textAbstract:
Le present travail est consacre a l'etude de guides d'ondes planaires d'oxyde de titane (tio#2), dopes avec des ions erbium et europium, fabriques par le procede sol-gel. La synthese du sol precurseur de tio#2 ainsi que le protocole utilise pour le depot des couches sont decrits en detail. Les proprietes de guidage, obtenues des une temperature d'elaboration relativement basse (100 c), sont utilisees pour suivre la densification de ces guides et pour la determination de leur coefficient d'attenuation. Les parametres optogeometriques (indice de refraction et epaisseur) sont determines par spectroscopie des lignes noires. La rugosite de surface est mise en evidence par microscopie a force atomique (afm). La potentialite du procede sol-gel dans le domaine de l'optique integree est illustree par le matricage de microstructures (reseaux) dans les guides de tio#2. La technique de spectroscopie raman en configuration guidee, est utilisee pour l'etude de la densification de ces guides, notamment pour suivre le processus de cristallisation. Dans le meme but, le dopage avec des ions europium trivalents fournit une information plus locale. Enfin, les proprietes spectroscopiques (fluorescence et durees de vie) de l'ion erbium dans les guides de tio#2, sont etudiees en fonction du taux de dopage (0,1 a 15%) et de la temperature de recuit: l'emission de fluorescence a 1,5 m (#4i#1#3#/#2#4i#1#5#/#2) ainsi que celle de up-conversion sont analysees en configuration guidee. L'influence des groupements hydroxyles sur les declins de fluorescence est suffisamment reduite par un traitement des couches a 600 c. A cette temperature, le maximum de la duree de vie du niveau #4i#1#3#/#2 (4 ms) est atteint dans le cas des guides dopes a 0,1% en ion erbium. Les declins de fluorescence sont ensuite analyses dans l'approximation de judd-ofelt
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Onaran, Özlem, Engelbert Stockhammer, and Lucas Grafl. "The finance-dominated growth regime, distribution, and aggregate demand in the US." Inst. für Volkswirtschaftstheorie und -politik, WU Vienna University of Economics and Business, 2009. http://epub.wu.ac.at/1306/1/document.pdf.
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The finance-dominated growth regime has affected key macroeconomic variables in several contradictory ways. This paper investigates some of these effects: an increase of rentiers income, housing wealth and net financial wealth on private consumption expenditures and the effects of changes in payments to the rentier by the business on private investment expenditures. A Post-Kaleckian macro model is used as a starting point for this investigation. The paper thus contributes to two debates. First, it aims at clarifying some important macroeconomic effects of financialization. Second, it extends the analysis of distribution-led demand regimes by controlling for financialization variables.Series: Department of Economics Working Paper Series
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Kubin, Ingrid, and Thomas Zörner. "Human Capital in a Credit Cycle Model." WU Vienna University of Economics and Business, 2017. http://epub.wu.ac.at/5681/1/wp251.pdf.
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We augment a model of endogenous credit cycles by Matsuyama et al.(2016) with human capital to study the impact of human capital on the stability of central economic aggregates. Thus we offer a linkage between human capital formation and credit market instability on a macrolevel combined with an analysis of functional income distribution. Human capital is modelled as pure external effect of production following a learning-by-producing approach. Agents have access to two different investment projects, which differ substantially in their next generations spillover effects. Some generate pecuniary externalities and technological spillovers through human capital formation whereas others fail to do so and are subject to financial frictions. Due to this endogenous credit cycles occur and a pattern of boom and bust cycles can be observed. We explore the impact of human capital on the stability of the system by numerical simulations which indicate that human capital has an ambiguous effect on the evolution of the output. Depending on the strength of the financial friction and the output share of human capital it either amplifies or mitigates output fluctuations. This analysis shows that human capital is an essential factor for economic stability and sustainable growth as a high human capital share tends to make the system's stability robust against shocks.Series: Department of Economics Working Paper Series
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Gächter, Martin, Martin Geiger, Florentin Glötzl, and Helene Schuberth. "Sectoral Deleveraging in Europe and Its Economic Implications." Oesterreichische Nationalbank, 2015. http://epub.wu.ac.at/6272/1/foeei.pdf.
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We examine net lending/net borrowing and the underlying debt dynamics at the sectoral level
in the European Union. Saving and investment patterns indicate that there have been considerable
deleveraging efforts since the start of the global financial crisis, particularly in the
nonfinancial
corporate and household sectors. In many EU countries, however, this decline in
credit transactions has not yet led to a significant reduction of sectoral debt-to-GDP ratios.
Subdued output growth and low or even negative inflation rates have undermined the
deleveraging
process and increased real debt burdens in a number of European economies.
Since these are often the countries that had experienced strong credit booms prior to the
crisis,
rebalancing needs are likely to persist and may be a significant drag on the recovery in
the near future. Furthermore, most of the ongoing rebalancing - both in terms of debt levels
and current account deficits - is based on a sharp decline in investment rather than an
increase in saving, which might lead to lower potential growth in the future. Recent developments may even jeopardize the catching-up process of peripheral euro area countries and non-euro area EU Member States in Central, Eastern and Southeastern Europe.
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Remonte, Ádamo Rossano Vicentini. "Síntese e caracterização de nanocompósitos vitrocerâmicos transparentes a base de SiO2-ZrO2 dopados com íons Eu3+ e Er3+ via processo sol-gel." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/59/59138/tde-26052009-165942/.
Full textAbstract:
A preparação de vitrocerâmicas transparentes a base de SiO2-ZrO2 dopado com íons Eu3+ e Er3+ através da metodologia sol-gel foi o objetivo desta dissertação. São apresentados resultados estruturais e óticos deste sistema, em função de temperatura, tempo e composição (variando-se a concentração de zircônia). Os sóis foram preparados em meio ácido e deixados em repouso até evaporação total do solvente, obtendo-se assim monolitos amorfos, os quais foram submetidos a tratamentos a 900, 1000 e 1100ºC durante 2, 4 e 8 horas visando eliminação de resíduos orgânicos, moléculas de água, grupos hidroxilas e densificação do material. O processo de densificação com os tratamentos leva a formação inicial da fase tetragonal de ZrO2. Foi observado o crescimento de nanopartículas de ZrO2 com dimensão dependente do tempo e temperatura de tratamento térmico, além da composição do nanocompósito. As nanopartículas obtidas apresentam tamanho que variam entre 3,1 a 5,5 nm, observadas por microscopia eletrônica de transmissão. A partir da adição de 20% de óxido de zircônio é possível observar uma mistura de fases entre tetragonal e monoclínica, resultado este evidenciado principalmente por espectroscopia Raman. Neste trabalho, o íon Eu3+ foi usado como sonda estrutural e um possível luminóforo na região do vermelho. Íons lantanídeos encontram-se parcialmente distribuídos na rede amorfa à base de sílica, apresentando um tempo de vida do 5D0 de 1,5 ms e em óxido de zircônio, com um tempo de vida de 2,7 ms. À medida que ocorre cristalização, aumenta-se a proporção de íons no óxido de zircônio, sugerindo que os íons lantanídeos preferencialmente encontram-se distribuídos em regiões ricas de ZrO2. Todas as amostras dopadas com íons Er3+ apresentam emissão no infravermelho próximo, na região da banda C utilizada em telecomunicações. A emissão do íon Er3+ em 1532 nm, atribuída à transição 4I13/2 4I15/2, apresentou uma largura a meia altura que variou entre 29 a 56 nm, dependendo da composição e do tratamento térmico realizado. O tempo de vida (1/e) do estado excitado 4I13/2 é de 5,3 ms a 6,5 ms dependendo do tratamento térmico.The preparation of transparent glass-ceramic based on the SiO2-ZrO2 doped with Eu3+ and Er3+ ions by the sol-gel methodology was the aim of this work. The structural and optical properties of the systems as a function of the time and temperature of annealing and also zirconium concentration are presented. The sol was prepared in acid solution and left in rest until total evaporation solvent, to obtaining the amorphous monoliths. The follow, the growthing of ZrO2 nanoparticles were induced and by the Transmission Electron Microscopy sizes between 3.1 and 5.5 nm were observed to be dependent to the time and temperature of annealing. The densification from the annealing at 900, 1000 and 1100ºC initially takes the formation of the tetragonal phase of ZrO2, and after 20 mol% of zirconium oxide is observed a mixture of phases between the tetragonal and monoclinic phase, result this evidenced by Raman spectroscopy. In this work the Eu3+ ion was used as a structural and possible luminescent material in the red region, displaying a life time value between 1.4 - 2.3 ms, for samples contend 0.3 mol% of Eu3+. The life time values increases as a function of time and temperature of annealing due the increase of the crystallinity of material that decreases the sites number of Eu3+ ions on the system. The Er3+ ions emission assigned to 4I13/2 4I15/2 localized around 1532 nm, showed a full width half maximum between 29 and 56 nm. The lifetime measurements were realized for Er3+ ions. The larger values of lifetime obtained are correspondent to samples with less crystalinity. Samples annealed in less temperatures show 5.3 ms of lifetime while samples annealed in higher temperatures show 6.5 ms of lifetime.
28
Bodiou, Loïc. "Etude des mécanismes d’excitation et d’émission de couches minces de nitrure de gallium dopées Eu3+, Er3+ et Tm3+ pour nouveaux dispositifs électroluminescents." Caen, 2007. http://www.theses.fr/2007CAEN2039.
Full textAbstract:
Cette thèse porte sur les mécanismes d’excitation et d’émission des couches minces de nitrure de gallium dopées par des ions de terre rare (Eu3+, Er3+ et Tm3+) suite à une excitation optique (photoluminescence) ou électrique (électroluminescence) du matériau semi-conducteur. A l’intérieur du GaN, deux catégories de site d’incorporation d’ions de terre rare peuvent être distinguées, à savoir les ions de terre rare "isolés" (c’est-à-dire ne contenant aucun défaut dans leur voisinage) et les complexes associant un ion de terre rare avec un piège, celui-ci pouvant provenir du dopage lui-même ou d’un défaut cristallin. L’excitation non-résonante est réservée au second type de centres et a lieu par transfert d’énergie lors de la recombinaison non radiative d’un exciton lié sur un piège proche de la terre rare. La comparaison d’échantillons de GaN dopés in situ et par implantation ionique par l’ion Eu3+ montre que ces films présentent chacun deux types de complexes "Eu3+-piège" dont l’un est commun à tous les échantillons. Les différences d’efficacité d’excitation respectives des deux complexes s’expliquent par la proximité du piège correspondant. Grâce à des expériences pompe-sonde combinant des lasers impulsionnel et continu, le chemin d’excitation des ions de terre rare est confirmé expérimentalement et deux des mécanismes d’extinction de leur luminescence (la photo-ionisation de pièges et l’effet Auger avec des porteurs libres) sont étudiés. L’excitation électrique du GaN:Er3+ est également présentée. Les études en fonction de la température, du courant parcourant l’échantillon ou de la tension de polarisation mettent en évidence l’excitation par impact des ions de terre rareThe PhD dissertation is devoted to the understanding of the excitation and quenching mechanisms of rare-earth (Eu3+, Er3+ and Tm3+) doped gallium nitride thin films. Rare-earth doping of GaN thin films results in two different types of incorporation sites for rare-earth ions: "isolated" ions (without any defect in their vicinity) and "rare-earth - trap" complexes. This trap can originate from the lattice distortion induced by the doping itself or from defects. Non-resonant excitation is reserved to this second kind of centres and occurs by energy transfer arising from the non radiative recombination of an exciton trapped in the vicinity of the rare-earth ion. Eu-implanted and in situ doped gallium nitride samples have been compared. Each presents two optically active "rare-earth - trap" complexes, one of which is common to all samples. Excitation efficiency differences between these complexes are found to be dependent on the distance between the trap and the rare-earth ion. Pump-probe experiments confirm experimentally the excitation path towards rare-earth ions and allow the study two quenching mechanisms namely photo-ionisation of traps and Auger effect with free carriers. Electroluminescence of GaN:Er3+ is also presented. Temperature, current and voltage dependant measurements indicate that electrical excitation of rare-earth ions take place by impact excitation
29
Aiginger, Karl. "The Great Recession versus the Great Depression: Stylized Facts on Siblings That Were Given Different Foster Parents." Kiel Institute for the World Economy, 2010. http://dx.doi.org/10.5018/economics-ejournal.ja.2010-18.
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This paper compares the depth of the recent crisis and the Great Depression. We use a new data set to compare the drop in activity in the industrialized countries for seven activity indicators. This is done under the assumption that the recent crisis leveled off in mid-2009 for production and will do so for unemployment in 2010. Our data indicate that the recent crisis indeed had the potential to be another Great Depression, as shown by the speed and simultaneity of the decline in the first nine months. However, if we assume that a large second dip can be avoided, the drop in all indicators will have been smaller than during the Great Depression. This holds true specifically for GDP, employment and prices, and least for manufacturing output. The difference in the depth in the crises concurs with differences in policy reaction. This time monetary policy and fiscal policy were applied courageously, speedily and partly internationally coordinated. During the Great Depression for several years fiscal policy tried to stabilize budgets instead of aggregate demand, and either monetary policy was not applied or was rather ineffective insofar as deflation turned lower nominal interest rates into higher real rates. Only future research will be able to prove the exact impact of economic policy, but the current tentative conclusion is that economic policy prevented the recent crisis from developing into a second Great Depression. This is also a partial vindication for economists. The majority of them might not have been able to predict the crisis, but the science did learn its lesson from the Great Depression and was able to give decent policy advice to at least limit the depth of the recent crisis. (author's abstract)
30
Antonakakis, Nikolaos, and Johann Scharler. "The synchronization of GDP growth in the G7 during US recessions." Taylor & Francis, 2012. http://epub.wu.ac.at/3468/1/BC_dcc_final_AEL.pdf.
Full textAbstract:
Using the dynamic conditional correlation (DCC) model due to Engle (2002), we estimate time varying correlations of quarterly real GDP growth among the G7 countries. In general, we find that rather heterogeneous patterns of international synchronization exist during US recessions. During the 2007-2009 recession, however, international co-movement increased substantially. (authors' abstract)
31
Smithin, John. "The rate of interest, economic growth, and inflation. An alternative theoretical perspective." Inst. für Volkswirtschaftstheorie und -politik, WU Vienna University of Economics and Business, 2002. http://epub.wu.ac.at/1458/1/document.pdf.
Full textAbstract:
The premise of this paper is that in a monetary production economy, policy decisions of the central bank, or more generally the 'monetary authority', set the tone not only for nominal interest rates but also for 'real' interest rates defined in the usual way. This is a different question than that of which institution(s) acquire the status of monetary authority at any particular stage of socioeconomic or technological development. Rather the suggestion is that the existence of some such social structure is a prerequisite if anything resembling capitalist monetary production is to be viable. The paper demonstrates that a coherent macroeconomic theory can be elaborated on this basis, including an explanation of economic growth, the business cycle, inflation, the functional distribution of income, the 'Keynesian' problem of the impact of demand growth on economic growth, endogenous money, cumulative causation, and endogenous technical change. (author's abstract)Series: Working Papers Series "Growth and Employment in Europe: Sustainability and Competitiveness"
32
Barbier, Anne. "Expression et caractérisation structurale de trois isoformes d'apolipoprotéine E humaine, E2, E3 et E4." Nancy 1, 1998. http://www.theses.fr/1998NAN10349.
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Antonakakis, Nikolaos. "Business Cycle Synchronization During US Recessions Since the Beginning of the 1870s." Elsevier, 2012. http://epub.wu.ac.at/3602/1/BC_1870%2D2011_EconLet_PrePrint.pdf.
Full textAbstract:
This paper examines the synchronization of business cycles across the G7 countries during US recessions since the 1870s. Using a dynamic measure of correlations, results depend on the globalization period under consideration. During the 2007-2009 recession, business cycles co-movements increased to unprecedented levels. (author's abstract)
34
Burden, Morwenna J. "The regulation of E2F." Thesis, University of Glasgow, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341993.
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Le, Boulch Marie. "Décryptage des mécanismes d’ubiquitylation régulant l’histone centromérique CenH3 chez Saccharomyces cerevisiae." Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1B009.
Full textAbstract:
L’ubiquitylation consiste en l’attachement covalent de l’ubiquitine sur d’autres protéines. Ce processus fait intervenir successivement trois familles d'enzymes : d’activation (E1s), de conjugaison (E2s) et de ligation (E3s) de l’ubiquitine. Lors de ma thèse, je m’intéresse au réseau d’enzymes d’ubiquitylation qui régule Cse4, l’histone variant localisée spécifiquement au centromère. Cse4 est une protéine essentielle qui permet une ségrégation correcte des chromosomes. Lorsqu’elle est trop exprimée, Cse4 peut se localiser sur la chromatine noncentromérique ce qui entraîne une instabilité génétique observée dans de nombreux cancers. Chez la levure, l’ubiquitylation empêche cette mauvaise localisation en menant à la dégradation de Cse4, mais les mécanismes précis ne sont pas connus et les données ont été obtenues en surexprimant Cse4. Notre hypothèse est que chez la levure, Cse4 endogène pourrait être régulée différemment grâce à plusieurs couples d’enzymes E2/E3. Dans ce contexte, l’objectif de ma thèse est de réaliser une étude détaillée du réseau d’enzymes impliqué dans l’ubiquitylation de Cse4 exprimée de façon endogène afin de mieux comprendre sa régulation. Nous avons pu notamment mettre en évidence une variation de l’ubiquitylation de Cse4 au cours de la phase S dépendant de l’E3 Psh1Ubiquitylation consists of the covalent attachment of ubiquitin to other proteins. This process successively involves three families of enzymes: activation (E1s), conjugation (E2s) and ligation (E3s) enzymes. In my thesis, I am interested in the ubiquitylation network that regulates endogenous Cse4, the variant histone specifically located at the centromere. Cse4 is an essential protein that allows proper segregation of chromosomes. When Cse4 is over-expressed, it can localize on noncentromeric chromatin resulting in genetic instability observed in many cancers. In budding yeast, ubiquitylation prevents mislocalisation of Cse4 by leading to its degradation, but precise mechanisms are not known and data were obtained by overexpressing Cse4. Our hypothesis is that in yeast, endogenous Cse4 could be regulated differently thanks to several pairs of E2 / E3 enzymes. In this context, the goal of my thesis is to carry out a detailed study of the network of enzymes involved in endogenously expressed Cse4 ubiquitylation in order to better understand its regulation. In particular, we have been able to show a variation of the ubiquitylation during S phase dependent of the E3 Psh1
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Markson, Gabriel Benjamin. "A systematic analysis of the E1, E2, and E3 interactions within the human protein ubiquitination system." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612409.
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Williams, Diane Keith. "Particle Size Dependence on the Luminescence Spectra of Eu3+:Y2O3 and Eu3+:CaO." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/29719.
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Since the Eu3+ ion can occupy different cation sites in a host material, it can serve as a useful probe of nanocrystalline structures to gain more insight into the structural changes that can occur when the particle size is reduced from the bulk to nanometer regime. The use of laser spectroscopy to probe two nanocrystalline structures, Eu3+:Y2O3 and Eu3+:CaO, was investigated. The nanocrystalline structures were prepared by the laser-vaporization-gas-phase condensation of the bulk oxides. The particle size distribution and dominant particle diameters of the nanocrystals were determined by transmission electron microscopy.
The particle size dependency results of Eu3+:Y2O3 revealed three distinct phases: (1) the sharp lines of the monoclinic Y2O3 were dominant in the larger particles; (2) the C2 site of the cubic phase, which appears in the smaller particles; and (3) the amorphous phase that increases in intensity as the particle size decreases. The observation of distinct spectral lines from the monoclinic phase confirms the presence of a crystalline phase for all of particle sizes studied.
The site-selective results of various concentrations of 13-nm Eu3+:CaO showed that the laser-vaporization-gas-phase condensation method of preparation produced two europium-containing phases at most concentrations: cubic CaO and monoclinic Eu2O3. Results showed that the monoclinic Eu2O3 phase could be reduced by 95% by annealing at 800 0C for 30 minutes without particle growth.
Since the Eu3+ ion and the Y3+ ion are isovalent, the substitution of a Eu3+ ion into Y2O3 is considered a trivial case of extrinsic disorder since the impurity is neutral relative to a perfect crystal1. As a result, it is not necessary to have any other defects present in the crystals to maintain charge neutrality. With Eu3+:CaO, the dopant and host cation charges are different and therefore the dopant distribution can be investigated by site-selective spectroscopy.
Since the experimental dopant distribution results for nanocrystalline Eu3+:CaO were inconclusive, a model to predict the theoretical change in the dopant distribution in Eu3+:CaO as a function of particle size was developed. The model predicts that the defect chemistry is affected when the particle size is approximately 50 nm and smaller.Ph. D.
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Fógia, Michelly Patrícia Santana de Almeida. "Síntese e caracterização de materiais do sistema ternário SiO2-ZnO-TiO2 obtido por sol-gel/Pechini." Universidade Federal de Goiás, 2014. http://repositorio.bc.ufg.br/tede/handle/tede/4390.
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In this work the structural and optical properties of SiO2-ZnO-TiO2 system doped with of Eu3+ (1% in mol) or Er3+ ions (0,2% to 2,0% in mol) were investigated. The compositions xSiO2-([100-x]/2)ZnO-([100-x]/2)TiO2 with x ranging from 40 to 80 were synthesized and studied. A mixed methodology using the traditional sol-gel process and Pechini method was employed to prepare stable and transparent sols, homogeneous gels, powders and transparent thin films without cracks. The prepared powders were heat treated from 100°C to 1100°C. The optical “band gap” values, the lifetime of Eu3+ 5D0 level, the R/O ratio of Eu3+ emissions and refractive index are dependent on the composition and thermal treatment of the powders. Multilayered thin films were deposited onto silica substrates using the “spin coating” technique. Afterwards, the as-prepared thin films were calcined at 500°C followed by annealings from 700°C to 1000°C. The X-ray diffraction of powders showed that the crystallization starts at 800°C with a mixture of zinc titanate phases (ZnTiO3, Zn2TiO4) and titanium rutile (TiO2). In compositions with low silica content (x = 40 or 50) the formation of zinc silicate (Zn2SiO4) occurs at high temperatures. The optical properties were evaluated for both powders and thin films. Particularly, thin films exhibit transmittance above 80% in the visible region. The refractive index at 632.8 nm and thickness of thin films were estimated using the envelope method and m-Line spectrocopy. Furthermore, morphological analysis of the thin films surface was performed by scanning electron microscopy. The characteristic emission peaks of Er3+ or Eu3+ doped powders and thin films were measured. The photoluminescent emission of Eu3+ ions, obtained the highest intensities for the powders treated at 800°C, for films treated at 700°C, under excitation at 394 nm, where the system remains primarily amorphous. The photoluminescent emission of the Er3+ ions was more intense for the powders treated at 1100°C under excitation at 980 nm, mainly due to reduction of hydroxyl groups which act as photoluminescence quenchers. In the film the highest intensity occurred at a temperature of 700°C under excitation at 378 nm and showing only one guided mode. Thus, the obtained thin films can be suitable for application as waveguides in integrated optical systems. Moreover, the Eu and Er doped powders can be used as phosphors in displays.
Este trabalho avalia as propriedades estruturais e ópticas do sistema ternário SiO2-ZnO-TiO2 dopado com íons Eu3+ (1% em mol) ou Er3+ (0,2% a 2,0% em mol). As composições xSiO2-([100-x]/2)ZnO-([100-x]/2)TiO2, com x = 40, 50, 60, 70 e 80 foram estudadas. Através de metodologia mista do processo sol-gel com o método Pechini foi possível obter sóis estáveis e transparentes, géis homogêneos, pós tratados termicamente de 100ºC a 1100°C e filmes finos transparentes e sem trincas. Filmes finos multicamadas foram depositados sobre substratos de sílica usando “spin coating” e calcinados a 500°C, seguido de um tratamento térmico entre 700°C e 1000°C. Por fotoluminescência foram observadas as transições de emissão características de íons Er3+ e Eu3+. A caracterização por difração de raios X dos pós mostrou que a cristalização tem início a partir de 800°C, com uma mistura de fases de titanatos de zinco (ZnTiO3, Zn2TiO4) e segregação de titânio rutilo (TiO2). Em composições com menores proporções de sílica (x= 40 ou 50) também ocorreu a formação de silicato de zinco (Zn2SiO4) em temperaturas mais elevadas. Os espectros de transmissão dos filmes apresentaram transmitância superior a 80%. Os valores de “band gap” óptico, o tempo de vida, as razões R/O e o índice de refração são dependentes do tratamento térmico e da composição dos pós. Usando o método da envoltória, pôde-se calcular o índice de refração a 632,8 nm e a espessura dos filmes finos, sendo que esta também foi estimada por microscopia eletrônica de varredura (MEV) e espectroscopia m-Line. A emissão fotoluminescente dos íons Eu3+ tem maior intensidade nos pós tratados à 800°C e nos filmes tratados à 700°C, sob excitação a 394 nm. Nestas temperaturas o sistema permanece predominantemente amorfo. A emissão fotoluminescente dos íons Er3+ foi mais intensa para os pós tratados a 1100°C, sob excitação a 980 nm, devido à eliminação de grupos OH supressores das emissões de Er3+. Nos filmes a maior intensidade se deu à temperatura de 700°C, sob excitação a 378 nm. Os filmes apresentaram apenas um modo guiado, sendo o mais apropriado para uso como guia de onda e os pós são indicados como fósforos podendo ser aplicados em “displays".
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Kharbache, Hayat. "Propriétés de fluorescence de l'ion Eu3+ dans K2(Y, Gd)F5 : analyse des couplages Eu3+-Eu3+ et des mécanismes de division de photons." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2008. http://tel.archives-ouvertes.fr/tel-00728845.
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La spectroscopie de fluorescence induite par laser et par rayonnement synchrotron a été utilisée pour analyser l'intense émission de l'ion Eu3+ dans les fluorures K2YF5 et K2GdF5. L'utilisation conjuguée de la spectroscopie résolue dans le temps, de la variation de la concentration en ions Eu3+ a permis d'identifier les niveaux électroniques de l'ion Eu3+ après excitation dans les niveaux 5D2, 5D1 et 5D0. Les répartitions spectrales de la fluorescence se corrèlent parfaitement avec un ion Eu3+ inséré dans un site de symétrie C1 . A basse température, en dessous de 100 K, des structures satellites apparaissent de part et d'autre des raies principales d'excitation 7F0 -> 5D0-2. L'analyse des évolutions spectrales et temporelles des fluorescences à partir du niveau 5D0 sous excitation sélective dans les raies principales d'excitation et dans les raies satellites en fonction de la température et de la concentration en ion EU3+ a permis d'attribuer les structures supplémentaires à des signatures de paires Eu3+-Eu3+ dont l'existence est favorisée par le caractère unidimensionnel de la structure cristallographique, y compris le composé K2EuF5. Des mécanismes de cascades et de divisions de photons impliquant les ions Gd3+ et Eu3+ ont été identifiés dans K2GdF5 sous excitation VUV. Finalement le caractère unidimensionnel de la structure s'avère être un handicap pour réaliser des luminophores à rendement quantique supérieur à l'unité.
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Brett, Tricia Korrin. "The fate of estrone (E1), 17beta-estradiol (E2), estriol (E3) and 17alpha-ethinylestradiol (EE2) in surface waters." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/46253.
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Lakes and rivers receiving wastewater treatment plant effluent contain many different endocrine disrupting compounds. Previous research into the fate of these compounds has focused on laboratory experiments that investigate a single scavenging mechanism, and there has been little research on the overall loss rate constants in receiving waters. This study evaluated the fate of estrone (E1), 17??-estradiol (E2), estriol (E3) and 17??-ethinylestradiol within three different receiving waters (a river, a large lake and a small reservoir) represented by two different mathematical models (plug flow reactor and continuously stirred tank reactor) and three different hydraulic residence times (<8 hours, >50 years and about 1 year). Wastewater treatment plant effluent samples and receiving waters were analysed for the four estrogens over a one year period. E1 and E2 were the only compounds detected and there was only enough data determine the fate of E1. A receiving water loss rate constant for E1 was calculated assuming first-order reaction kinetics. E1 loss was not detectable in the river and the large lake due to a very short and very long residence time, respectively. The time-weighted E1 loss rate constant within the small reservoir was found to be 0.0106 d-??. Data suggested that there may be a seasonal component to this loss rate that requires further investigation. The rate constant found suggests that E1 can be transported great distances within rivers.
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Morris, Lorna Josephine. "Regulation of E2F by phosphorylation." Thesis, University of Glasgow, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398675.
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Santana, Ricardo Costa de. "Espectroscopia de centros opticamente ativos em cristais de Ca3Ga2Ge3O12 dopados com Er3+ e Er3+,Cr3+." Universidade de São Paulo, 1999. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-13062008-110813/.
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O objetivo principal deste trabalho foi identificar e separar os níveis de energia dos multipletos excitado, 4S3/2, e fundamental, 4I15/2, provenientes do íon Er3+ alojado nos vários sítios não equivalentes existentes no garnet Ca3Ga2Ge3O12. Várias técnicas de espectroscopia óptica (absorção, luminescência com bombeio seletivo, excitação e conversão ascendente de luz) foram usadas com este objetivo. A partir dos resultados experimentais foram calculados, pela primeira vez, os parâmetros de íon livre e de campo cristalino para o Er3+ em cada um dos sítios identificados. Experimentos de luminescência e absorção sob a influência de campo magnético também foram realizados, e o fator g tanto do estado 4S3/2 quanto do 4I15/2 do Er3+ neste garnet foram determinados.The main objective of this work was to identify and attribute the energy levels of excited 4S3/2 and ground 4I15/2states, corresponding to the Er3+ ions located at the various non equivalent sites present in the Ca3Ga2Ge3O12 garnet. Several optical spectroscopic techniques, (absorption, site-selective luminescence, excitation and upconversion of light), were used with this objective. From the experimental results, it was possible, for the first time, to calculate the free ion parameters, as well as the crystalline field parameters, for the Er3+ ions in each of the identified sites. Luminescence experiments and absorption under the influence of the magnetic field were performed, and the g factor associated to both, 4S3/2 and 4I15/2 estates in this garnet were determined.
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Figueiredo, Marcio da Silva [UNESP]. "Avaliação óptica de vidros teluritos preparados com Er3+ e Er3+/Yb3+ para aplicação em fotônica." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/102527.
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figueiredo_ms_dr_ilha.pdf: 1006805 bytes, checksum: 5c550a3c14783fc554cc37dba6517cff (MD5)No presente trabalho foram sintetizados vidros Te-Li-Ti (TLT) dopados com Er3+ e também codopados com Er3+/Yb3+ para o estudo das propriedades da emissão em 1,5m do íon. Inicialmente foi estudado um conjunto com diferentes concentrações de Er3+ para ver a dependência com a concentração de dopante da eficiência quântica de emissão (). Foi empregado como método experimental de análise a técnica de lente térmica (LT) e os resultados foram confrontados com os determinados usando dados espectroscópicos combinados com a teoria de Judd-Ofelt. Embora sejam fortemente dependentes com a concentração, os valores de para as concentrações mais baixas de dopante (~76% para o vidro TLT: 0,05% molar de Er2O3) são maiores que os valores reportados na literatura para o mesmo íon em outras matrizes teluritos. Adicionalmente, o sistema codopado com Er3+/Yb3+ foi estudo a fim de avaliar se a adição do Yb3+ na matriz promove o aumento da emissão do érbio em 1,5 m, excitando o nível emissor via Yb3+. Os resultados mostraram que há um eficiente mecanismo de transferência de energia do Yb3+ para o Er3+ de maneira que a intensidade de emissão no infravermelho foi aumentada. Ademais, avaliou-se a existência ou não da emissão “downconversion” em 980 nm do itérbio mediante excitação do Er3+ no visível. Do ponto de vista do “downconversion”, que é interessante para aplicação do material em placas solares à base de silício, os resultados mostraram, pela primeira vez em um vidro telurito, que o efeito ocorre com uma eficiência na transferência de energia do Er3+ para o Yb3+ de 56%, indicando que o material tem boa perspectiva para utilização comercial
In this paper Er3+ doped and Yb3+/ Er3+codoped Te-Li-Ti (TLT) glasses were synthesized to study the properties of the emission at 1.5 m. One set was initially studied with different Er3+ concentrations to see the dependence of emission quantum efficiency () with the dopant concentration. The thermal lens spectrometry (TL) was employed as the method of experimental analysis and the results were compared with those determined using spectroscopic data combined with the Judd-Ofelt theory. Although they are highly dependent on the concentration, the values for the lower dopant concentrations (~ 76% for the TLT glass doped with 0.05 mol% Er2O3) are higher than those reported in literature for the same ion at tellurite other matrices. Additionally, the Er3+ / Yb3+ codopado system was studied to evaluate the increased emission of erbium at 1.5 m as a function of Yb3+ increment by excitation in the metastable state in Yb3+. The results show that there is an efficient transfer of energy from Yb3+ to Er3+, so that the infrared emission of Er3+ was increased, as was desired. Furthermore, we assessed whether or not the issue ytterbium downconversion emission at 980 nm upon excitation visible in the Er3+. From the viewpoint of the downconversion mechanism, which is interesting for application of the material in solar cells based on silicon, the results showed for the first time in a glass tellurite, which effect occurs with efficiency in energy transfer from Er3+ Yb3+ to 56%, indicating that the material has good prospects for commercial use
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Figueiredo, Marcio da Silva. "Avaliação óptica de vidros teluritos preparados com Er3+ e Er3+/Yb3+ para aplicação em fotônica /." Ilha Solteira, 2013. http://hdl.handle.net/11449/102527.
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Orientador: João Carlos Silos MoraesCoorientador: Sandro Márcio Lima
Banca: Eudes Borges de Araújo
Banca: Antonio Carlos Ferreira Seridonio
Banca: Noelio Oliveira Dantas
Banca: Luiz Antonio de Oliveira Nunes
Resumo: No presente trabalho foram sintetizados vidros Te-Li-Ti (TLT) dopados com Er3+ e também codopados com Er3+/Yb3+ para o estudo das propriedades da emissão em 1,5m do íon. Inicialmente foi estudado um conjunto com diferentes concentrações de Er3+ para ver a dependência com a concentração de dopante da eficiência quântica de emissão (). Foi empregado como método experimental de análise a técnica de lente térmica (LT) e os resultados foram confrontados com os determinados usando dados espectroscópicos combinados com a teoria de Judd-Ofelt. Embora sejam fortemente dependentes com a concentração, os valores de para as concentrações mais baixas de dopante (~76% para o vidro TLT: 0,05% molar de Er2O3) são maiores que os valores reportados na literatura para o mesmo íon em outras matrizes teluritos. Adicionalmente, o sistema codopado com Er3+/Yb3+ foi estudo a fim de avaliar se a adição do Yb3+ na matriz promove o aumento da emissão do érbio em 1,5 m, excitando o nível emissor via Yb3+. Os resultados mostraram que há um eficiente mecanismo de transferência de energia do Yb3+ para o Er3+ de maneira que a intensidade de emissão no infravermelho foi aumentada. Ademais, avaliou-se a existência ou não da emissão "downconversion" em 980 nm do itérbio mediante excitação do Er3+ no visível. Do ponto de vista do "downconversion", que é interessante para aplicação do material em placas solares à base de silício, os resultados mostraram, pela primeira vez em um vidro telurito, que o efeito ocorre com uma eficiência na transferência de energia do Er3+ para o Yb3+ de 56%, indicando que o material tem boa perspectiva para utilização comercial
Abstract: In this paper Er3+ doped and Yb3+/ Er3+codoped Te-Li-Ti (TLT) glasses were synthesized to study the properties of the emission at 1.5 m. One set was initially studied with different Er3+ concentrations to see the dependence of emission quantum efficiency () with the dopant concentration. The thermal lens spectrometry (TL) was employed as the method of experimental analysis and the results were compared with those determined using spectroscopic data combined with the Judd-Ofelt theory. Although they are highly dependent on the concentration, the values for the lower dopant concentrations (~ 76% for the TLT glass doped with 0.05 mol% Er2O3) are higher than those reported in literature for the same ion at tellurite other matrices. Additionally, the Er3+ / Yb3+ codopado system was studied to evaluate the increased emission of erbium at 1.5 m as a function of Yb3+ increment by excitation in the metastable state in Yb3+. The results show that there is an efficient transfer of energy from Yb3+ to Er3+, so that the infrared emission of Er3+ was increased, as was desired. Furthermore, we assessed whether or not the issue ytterbium downconversion emission at 980 nm upon excitation visible in the Er3+. From the viewpoint of the downconversion mechanism, which is interesting for application of the material in solar cells based on silicon, the results showed for the first time in a glass tellurite, which effect occurs with efficiency in energy transfer from Er3+ Yb3+ to 56%, indicating that the material has good prospects for commercial use
Doutor
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Ouseph, Madhu Micheal. "Atypical E2F repressors E2F7 and E2F8: Balancing E2F activity in normal and variant cell cycles." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1331055740.
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Peng, Lin [Verfasser], and Udo [Akademischer Betreuer] Jeschke. "The role of G-protein coupled prostaglandin E2 receptors (EP2 and EP3) in unexplained recurrent miscarriage and cervical cancer / Lin Peng ; Betreuer: Udo Jeschke." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2021. http://d-nb.info/1239049366/34.
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Bosco, Giácomo Bizinoto Ferreira 1987. "Luminescência do Eu3+ em a-SiNx:H." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278134.
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Orientador: Leandro Russovski TesslerDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
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Resumo: Neste trabalho estudamos a fotoluminescência (PL) do Eu3+ em filmes finos de subnitretos de silício amorfo hidrogenado (a-SiNx:H) dopados com európio. No total, 85 amostras do material foram preparadas por RF-sputtering reativo variando o conteúdo de nitrogênio e európio. A caracterização composicional foi feita por RBS (Rutherfod Backscattering Spectroscopy). Coeficientes de absorção, índices de refração e espessuras das amostras foram determinados por espectroscopia de transmitância ótica UV-VIS. A PL foi medida a temperatura ambiente e a 10K em função da temperatura de recozimento entre 250 e 1100°C sob atmosfera redutora de nitrogênio ou oxidante de oxigênio. Para as amostras recozidas em atmosfera de N2, não foi observada nenhuma PL proveniente dos íons Eu3+. Há, no entanto indicações da PL característica de íons Eu2+. Após quase um ano de tentativas frustradas de obter PL dos íons Eu3+ foram determinados os parâmetros das amostras que otimizam o processo: concentração de nitrogênio x em torno de 1,17, temperatura de recozimento de 1100oC em atmosfera de oxigênio e concentração de európio y = [Eu]/[Si] = 8,9 at%.. A emissão do Eu3+ em a-SiNx:H foi analisada pela teoria de campo cristalino usando um pacote de programas que otimiza os parâmetros de campo cristalino da camada f. Para isso, analisamos também o espectro do Eu2O3 em pó, usado como referencia. Assim confirmamos que os íons ativos de Eu3+ ocupam sítios de simetria pontual C2. A analise dos dados para a-SiNx:H sugere que nesse material os íons Eu3+ ocupam sítios com a mesma simetria encontrada em Eu2O3 mas muito mais suscetíveis aos efeitos de desordem. Considerando essa simetria e o tratamento térmico necessário, e razoável supor a formação de clusters de oxido de európio de dimensões nanométricas em torno dos íons Eu3+
Abstract: In this work we studied the photoluminescence (PL) of Eu3+ in europium doped hydrogenated amorphous silicon subnitrides thin films (a-SiNx:H). In total, 85 samples of the material were prepared by reactive RF-sputtering varying the nitrogen and europium contents. Compositional characterization was obtained by RBS (Rutherford Backscattering Spectroscopy). Absorption coefficients, refraction indexes ans sample thicknesses were determined by UV-VIS optical transmittance spectroscopy. The PL was measured at room temperature and at 10K as a function of the sample annealing temperature between 250 and 1100°C under a reductive nitrogen atmosphere or an oxidant oxygen atmosphere. For the N2 annealed samples, we did not observe any PL from Eu3+ íons. There are, however, indications of Eu2+ characteristic emission. After almost a year of frustrated attempts to obtain PL from Eu3+ ions the parameters which optimize the process were determined: nitrogen content x around 1,17, annealing temperature of 1100oC under oxygen atmosphere and europium content y = [Eu]/[Si] = 8,9 at%. The Eu3+ emission in a-SiN1,17:H was analyzed using crystal field theory and a program suite to optimize f-shell crystal field parameters. We also analyzed the PL spectrum of powder Eu2O3 to use as a reference. The data analysis for a-SiNx:H suggests that in this material the Eu3+ active ions occupy sites with the same C2 point symmetry found in Eu2O3 but much distorted due to disorder. Considering this symmetry and the sample treatment necessary to obtain the PL, it is reasonable suppose the formation of europium oxide nanometer scale clusters around the Eu3+ ions
Mestrado
Física
Mestre em Física
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Santos, Clenilton Costa dos. "Propriedades Ãpticas dos vidros Er3+:PbPO4." Universidade Federal do CearÃ, 2010. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=4874.
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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorNeste trabalho utilizamos vÃrias tÃcnicas para investigar as propriedades Ãpticas dos vidros fosfato de chumbo (PbPO4) com concentraÃÃes moderadamente altas de Ãons de Ãrbio (Er3+), EDLP. Medimos a susceptibilidade de terceira ordem, χ3, e a dispersÃo do Ãndice de refraÃÃo linear, n0(λ), dos vidros EDLP na regiÃo de comprimento de onda entre 400 e 1940 nm, por meio da tÃcnica de Franjas de Maker. A partir do valor de χ3, calculamos o Ãndice de refraÃÃo nÃo-linear, n2, cujo valor à cerca de cinco vezes maior que o da sÃlica (SiO2). TambÃm obtivemos os valores de n2 dos vidros EDLP, atravÃs da tÃcnica de varredura Z para vÃrios comprimentos de onda. A diferenÃa entre os valores obtidos pelas duas tÃcnicas foi de 15%. Realizamos medidas de absorÃÃo Ãptica, cujos dados foram utilizados para calcular os parÃmetros fenomenolÃgicos Ωλ da teoria de Judd-Ofelt. Observamos que Ω4 e Ω6 permanecem praticamente constante com o aumento da concentraÃÃo de Er3+, ao passo que Ω2 diminui. Excitando as amostras em 800 nm foi possÃvel verificar emissÃes no verde, vermelho e infravermelho, centradas em 530, 550, 660 e 1530 nm, respectivamente. O tempo de vida da transiÃÃo 4I13/2 → 4I15/2 (em 1530 nm) do Er3+ diminui com o aumento da concentraÃÃo de Er3+, refletindo o quÃo importante à o processo nÃo-radiativo associado a esta transiÃÃo. A teoria de McCumber foi usada para calcular, a partir da seÃÃo de choque de absorÃÃo, a seÃÃo de choque da emissÃo estimulada da transiÃÃo 4I13/2 → 4I15/2 do Er3+. Observamos e analisamos uma forte reabsorÃÃo da fluorescÃncia em 1530 nm. Finalmente, discutimos a aplicabilidade dos vidros EDLP em dispositivos fotÃnicos.
In this work we employ several techniques to investigate the optical properties of moderately high Er3+-doped lead phosphate (EDLP) glasses. The third-order optical susceptibility, χ3, and dispersion of the linear refractive index, n0(λ), of Er3+:PbPO4 were measured in the wavelength range between 400 and 1940 nm by using the spectrally resolved femtosecond Maker fringes technique. The nonlinear refractive index, n2, obtained from the third-order susceptibility was found to be five times higher than that of silica. For comparison purposes, the Z-scan technique was also employed to obtain the values of n2 of EDLP at several wavelengths, and the values obtained using the two techniques agree to within 15%. From the data obtained by absorption measurements, the Judd-Ofelt theory was employed to calculate the intensity-dependent parameters Ωλ (λ = 2, 4, and 6). We observed that increasing Er3+ content, Ω4 and Ω6 remain constant, while Ω2 decreases. Green, red, and infrared emissions centered at 530, 550, 660, and 1530 nm were observed under excitation at 800 nm. The lifetime of the Er3+: 4I13/2 → 4I15/2 (1530 nm) transition decreases with increasing Er3+ content, reflecting how significant the non-radiative process associated with this transition is. The McCumber theory was used to calculate, from absorption cross-section, the stimulated emission cross-section of the Er3+: 4I13/2 → 4I15/2 transition. A strong re-absorption of the fluorescence at 1530 nm was also observed and analyzed. Finally, we discuss the potential use of Er3+:PbPO4 glasses in photonics devices.
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Santos, Clenilton Costa dos. "Propriedades ópticas dos vidros Er3+:PbPO4." reponame:Repositório Institucional da UFC, 2010. http://www.repositorio.ufc.br/handle/riufc/9652.
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SANTOS, Clenilton Costa dos. Propriedades ópticas dos vidros Er3+:PbPO4. 2010. 96 f. Tese (Doutorado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2010.Submitted by Edvander Pires (edvanderpires@gmail.com) on 2014-11-03T18:38:41Z No. of bitstreams: 1 2010_tese_ccsantos.pdf: 4778732 bytes, checksum: e9324ded793c2e668aa603d0ce9ecc71 (MD5)
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In this work we employ several techniques to investigate the optical properties of moderately high Er3+-doped lead phosphate (EDLP) glasses. The third-order optical susceptibility, χ3, and dispersion of the linear refractive index, n0(λ), of Er3+:PbPO4 were measured in the wavelength range between 400 and 1940 nm by using the spectrally resolved femtosecond Maker fringes technique. The nonlinear refractive index, n2, obtained from the third-order susceptibility was found to be five times higher than that of silica. For comparison purposes, the Z-scan technique was also employed to obtain the values of n2 of EDLP at several wavelengths, and the values obtained using the two techniques agree to within 15%. From the data obtained by absorption measurements, the Judd-Ofelt theory was employed to calculate the intensity-dependent parameters Ωλ (λ = 2, 4, and 6). We observed that increasing Er3+ content, Ω4 and Ω6 remain constant, while Ω2 decreases. Green, red, and infrared emissions centered at 530, 550, 660, and 1530 nm were observed under excitation at 800 nm. The lifetime of the Er3+: 4I13/2 → 4I15/2 (1530 nm) transition decreases with increasing Er3+ content, reflecting how significant the non-radiative process associated with this transition is. The McCumber theory was used to calculate, from absorption cross-section, the stimulated emission cross-section of the Er3+: 4I13/2 → 4I15/2 transition. A strong re-absorption of the fluorescence at 1530 nm was also observed and analyzed. Finally, we discuss the potential use of Er3+:PbPO4 glasses in photonics devices.
Neste trabalho utilizamos várias técnicas para investigar as propriedades ópticas dos vidros fosfato de chumbo (PbPO4) com concentrações moderadamente altas de íons de érbio (Er3+), EDLP. Medimos a susceptibilidade de terceira ordem, χ3, e a dispersão do índice de refração linear, n0(λ), dos vidros EDLP na região de comprimento de onda entre 400 e 1940 nm, por meio da técnica de Franjas de Maker. A partir do valor de χ3, calculamos o índice de refração não-linear, n2, cujo valor é cerca de cinco vezes maior que o da sílica (SiO2). Também obtivemos os valores de n2 dos vidros EDLP, através da técnica de varredura Z para vários comprimentos de onda. A diferença entre os valores obtidos pelas duas técnicas foi de 15%. Realizamos medidas de absorção óptica, cujos dados foram utilizados para calcular os parâmetros fenomenológicos Ωλ da teoria de Judd-Ofelt. Observamos que Ω4 e Ω6 permanecem praticamente constante com o aumento da concentração de Er3+, ao passo que Ω2 diminui. Excitando as amostras em 800 nm foi possível verificar emissões no verde, vermelho e infravermelho, centradas em 530, 550, 660 e 1530 nm, respectivamente. O tempo de vida da transição 4I13/2 → 4I15/2 (em 1530 nm) do Er3+ diminui com o aumento da concentração de Er3+, refletindo o quão importante é o processo não-radiativo associado a esta transição. A teoria de McCumber foi usada para calcular, a partir da seção de choque de absorção, a seção de choque da emissão estimulada da transição 4I13/2 → 4I15/2 do Er3+. Observamos e analisamos uma forte reabsorção da fluorescência em 1530 nm. Finalmente, discutimos a aplicabilidade dos vidros EDLP em dispositivos fotônicos.
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Hampel, Constanze. "Deregulation of E2f-1 and chemosensitivity." Thesis, University College London (University of London), 2004. http://discovery.ucl.ac.uk/1446635/.
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The E2F transcription factors are key components of the retinoblastoma tumour suppressor pathway which control the progression from G1 to S phase in the cell cycle and regulate the transcription of proteins required for S-phase entry and DNA synthesis. Deregulation of E2F-1 expression results in the loss of control of normal cell cycle progression. Aberrations of the retinoblastoma pathway have been reported in most human cancers. Alteration in cell cycle regulation may alter the activity of anti-cancer drugs. An increase in E2F-1 activity and transcription of E2F-regulated genes potentially influences the cellular sensitivity to chemotherapeutic agents. This study aimed to investigate the pattern, mechanism and potential inhibition of E2F-1 interactions with chemotherapeutic agents. Initial experiments performed on an HT1080 cell line stably overexpressing E2F-1 suggested a role in resistance to several DNA interactive agents, in particular the minor groove binding alkylating agent BGIII21. However, further characterisation identified the HT1080 transfectants to be CHO cell lines. Experiments using an inducible E2F-1 cell line showed increased expression of E2F-1 to have a minimal effect on chemosensitivity to BGIII21. A decrease in chemosensitivity was observed in response to BGIIII21 in CHO cells. NER, homologous recombination or mismatch repair deficiency were not found to be the underlying causes for resistance in CHO cells. Experiments using E2F-1 inhibitory peptides, despite exhibiting marked inter-experimental variations, suggested an inverse correlation between endogenous E2F-1 expression level and peptide activity. Further, cell cycle analysis showed the E2F-1 inhibitory peptides to cause G1 arrest or apoptosis in leukemic cell lines. In conclusion, inhibition of E2F-1 activity through peptides was found to be a valuable but unreliable tool to influence the effect of chemotherapeutic agents on cells expressing increased levels of E2F-1 due to persistent variations in factors affecting peptide activity.