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The Global ETD Search service is a free service for researchers
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Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
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Showing 21 to 30 of 30 (0.021 seconds)| 21 |
Teoria efetiva para decaimentos radiativos do X(3872) / Effective Field Theory for the X(3872) Radiative DecaysDaniel Alberto Stanischesk Molnar 04 December 2015 (has links)
In this thesis we study radiative decays of the exotic meson X(3872) into $J/ \\psi \\gamma$ and $\\psi(2S) \\gamma$ using an effective field theory framework. Assuming the exotic meson to be primarily a molecular state of the mesons $D$ and $ \\bar{D}^{*}$, we perform a renormalization analysis to estimate the contribution of the short-distance physics. This is done using two different prescriptions, the popular $\\overline{MS}$ scheme, valid only for perturbative calculations, and the PDS scheme, used in EFTs for loosely-bound systems and intrinsically non-perturbative. We show that, without a short-distance contact interaction, the observables become very dependent on the regularization scale, therefore demanding proper renormalization. We include two short-distance contact terms, one for each decay channel, and impose the renormalization condition within both $\\overline{MS}$ and PDS schemes. We obtain the behavior of the contact term with the renormalization scale $\\mu$, which can be useful in guiding models for the short-distance part. We note, however, distinct behaviors between $\\overline{MS}$ and PDS. Both also lead to lower limits in the decay widths that could, in principle, be tested experimentally. / In this thesis we study radiative decays of the exotic meson X(3872) into $J/ \\psi \\gamma$ and $\\psi(2S) \\gamma$ using an effective field theory framework. Assuming the exotic meson to be primarily a molecular state of the mesons $D$ and $ \\bar{D}^{*}$, we perform a renormalization analysis to estimate the contribution of the short-distance physics. This is done using two different prescriptions, the popular $\\overline{MS}$ scheme, valid only for perturbative calculations, and the PDS scheme, used in EFTs for loosely-bound systems and intrinsically non-perturbative. We show that, without a short-distance contact interaction, the observables become very dependent on the regularization scale, therefore demanding proper renormalization. We include two short-distance contact terms, one for each decay channel, and impose the renormalization condition within both $\\overline{MS}$ and PDS schemes. We obtain the behavior of the contact term with the renormalization scale $\\mu$, which can be useful in guiding models for the short-distance part. We note, however, distinct behaviors between $\\overline{MS}$ and PDS. Both also lead to lower limits in the decay widths that could, in principle, be tested experimentally.
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Resonant Interactions of Dark Matter Particles Using Effective Field TheoryJohnson, Evan Wesley 06 November 2019 (has links)
No description available.
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Quem sabe ajudar a construir sonhos?: um estudo linguístico sobre um diário reflexivo de uma professora de língua estrangeiraBorborema, Márcia Ozinete de Alcântara Pinho 04 March 2011 (has links)
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Previous issue date: 2011-03-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This action-research placed in the field of Applied Linguistics has as general objective to investigate the representations of experience in a reflective journal of a researcher-teacher, in context of Educação de Jovens e Adultos in a public school at Paraíba, in relation to a literacy project in English as FL which aims to elaborate a cultural folder. More specifically, I objective to examine the ways of acting of the reflexive process (SMYTH, 1992) in relation to the practice of the researcher-teacher when developing the literacy project, deepening the analysis through the system of transitivity (HALLIDAY, 1994). To achieve the proposed objectives, this study is based on the theoretical assumptions on journals and reflective practice (BAILEY, 1990; ZABALZA 1994, 2004, LIBERALI, 1999; REICHMANN, 2001; TÁPIAS-OLIVEIRA, 2006, among others), on literacy practices (KLEIMAN, 1995, 2000; BARTON et al 2000; OLIVEIRA and KLEIMAN 2008; TINOCO, 2008; ROJO, 2008) and on Sistemic-Functional Linguistics (HALLIDAY, 1994). The results reveal that the way of acting occurred the most correspond to describing; it is also the most significant one. In relation to the researcher-teacher's representations concerning her own practice, it is verified that that representation happened, mainly, through the material Processes, portraying the concrete actions, including more Actors, i.e., the teacher and the students. It is possible to notice a great incidence of material Processes, that signalizes different doings suggesting a transformation of the researcher- teacher in terms of changes in foreign language teaching in context of EJA. In conclusion, this study demonstrates the importance of reflective journaling as a literacy practice and as an instrument of self-development tool, (re)signifying the role of the teacher. This study also underscores the need to reimagine English language teaching/learning process, emphasizing the importance of focusing on writing as a social practice and on literacy projects. / Esta pesquisa-ação situada no campo da Linguística Aplicada tem como objetivo geral investigar as representações da experiência em um diário reflexivo de uma professora-pesquisadora, em contexto de Educação de Jovens e Adultos em uma escola pública na Paraíba, em relação a um projeto de letramento em inglês como língua estrangeira, cujo intuito é a elaboração de um folder cultural. Mais especificamente, objetiva examinar as formas de ação do processo reflexivo (SMYTH, 1992) em relação à prática da professora-pesquisadora ao desenvolver o projeto de letramento, aprofundando a análise por meio do sistema de transitividade (HALLIDAY, 1994). Para atingir o objetivo proposto, este estudo está ancorado nos pressupostos teóricos sobre diários e prática reflexiva (BAILEY, 1990; SMYTH, 1992; ZABALZA 1994, 2004; ROMERO, 1998; LIBERALI, 1999; REICHMANN, 2001; TÁPIAS-OLIVEIRA, 2006, entre outros), práticas de letramento (KLEIMAN, 1995, 2000; BARTON et al 2000; OLIVEIRA e KLEIMAN 2008) e Linguística Sistêmico-Funcional, em especial, os Processos (HALLIDAY, 1994). A análise do corpus revela que a forma de ação mais recorrente e significativa corresponde a descrever. Em relação às representações da professora-pesquisadora, verificamos que ocorreram, principalmente, por meio de Processos materiais, inscrevendo fazeres e incluindo mais Atores, ou seja, a professora e os alunos. É possível perceber uma grande incidência de Processos materiais, que passam a sinalizar fazeres diferentes, sugerindo uma transformação da prática da professora-pesquisadora em termos de mudanças nas aulas de língua estrangeira em contexto de EJA. Concluindo, esta pesquisa demonstra a importância do diário reflexivo como prática de letramento e como instrumento de autoformação, proporcionando uma (re)significação do papel do professor, como também ressalta a necessidade de reinventar o processo de ensino-aprendizagem da língua inglesa, enfatizando a relevância de projetos de letramento, dando um maior enfoque na questão da escrita como prática social.
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An Effective Field Theory description of 3He-alpha Elastic ScatteringPoudel, Maheshwor January 2022 (has links)
No description available.
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Effective field theories of heavy-quark mesonsAlhakami, Mohammad Hasan M. January 2015 (has links)
We study the masses of the low-lying charm and bottom mesons within the framework of heavy-hadron chiral perturbation theory. We work to third order in the chiral expansion, where meson loops contribute. In contrast to previous approaches, we use physical meson masses in evaluating these loops. This ensures that their imaginary parts are consistent with the observed widths of the D-mesons. The lowest odd- and even-parity, strange and non-strange mesons provide enough constraints to determine only certain linear combinations of the low-energy constants (LECs) in the effective Lagrangian. We comment on how lattice QCD could provide further information to disentangle these constants. Then we use the results from the charm sector to predict the spectrum of odd- and even-parity of the bottom mesons. The predicted masses from our theory are in good agreement with experimentally measured masses for the case of the odd-parity sector. For the even-parity sector, the $B$-meson states have not yet been observed; thus, our results provide useful information for experimentalists investigating such states. The near degeneracy of nonstrange and strange scalar $B$ mesons is confirmed in our predictions using $\mathrm{HHChPT}$. Finally,we show why previous approaches of using $\mathrm{HHChPT}$ in studying the mass degeneracy in the scalar states of charm and bottom meson sectors gave unsatisfactory results. Interactions between these heavy mesons are treated using effective theories similar to those used to study nuclear forces. We first look at a strongly-interacting channel which produces a bound or virtual state and a dimer state which couples weakly to a weakly-interacting channel to produce a narrow resonance. We also look at the short-range interactions in two channels. We consider two cases: two channels where one has a strong $s$-wave interaction which produces bound or virtual states, and a dimer state which couples weakly to weakly-coupled channels which in turn can produce narrow resonances. For each of these systems, we use well-defined power-counting schemes. The results can be used to investigate resonances in the charmonium and bottomonium systems. We demonstrate how the method can be applied to the $X(3872)$. The widths of the $X(3872)$ for decay processes to $\bar{D}^0 D^{*0}$ and $\bar{D}^0D^0\pi$ are calculated. We use these results to obtain the line shapes of the $X(3872)$ under different assumptions about the nature of this state.
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Feelings of Enlightenment: A Hermeneutic Interpretation of Latent Enlightenment Assumptions in Greenberg's Emotion-Focused TherapyGomez, Alex A. 17 August 2018 (has links)
No description available.
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Beyond-mean-field corrections and effective interactions in the nuclear many-body problem / Des corrections au-delà de champ moyen et des interactions efficaces dans le problème à N corps nucléaireMoghrabi, Kassem 12 September 2013 (has links)
Les approches basées sur les modèles de champ moyen reproduisent avec succès certaines propriétés nucléaires comme les masses et les rayons, dans le cadre des théories de la fonctionnelle de la densité pour l'énergie (EDF). Cependant, plusieurs corrélations complexes sont absentes dans les théories de champ moyen et un certain nombre d'observables liées aux propriétés à une particule et collectives des systèmes nucléoniques ne peuvent pas être prédites avec précision. La nécessité de fournir une description précise des données disponibles ainsi que des prévisions fiables dans les régions exotiques de la carte nucléaire motive l'utilisation de modèles plus sophistiqués, qui vont au-delà du champ moyen. Des corrélations et des corrections d'ordre supérieur (au-delà du premier ordre, qui représente l'approximation de champ moyen) sont introduites dans ces modèles. Un aspect crucial dans ces calculs est le choix de l'interaction efficace qui doit être utilisée quand on va au-delà du premier ordre (les interactions efficaces existantes sont généralement ajustées avec des calculs de champ moyen). Dans la première partie de la thèse, nous traitons l'équation d'état de la matière nucléaire, évaluée jusqu'au deuxième ordre avec la force phénoménologique de Skyrme. Nous analysons la divergence ultraviolette qui est liée à la portée nulle de l'interaction et nous introduisons des interactions régularisées de type Skyrme qui peuvent être utilisées au deuxième ordre. Des procédures de régularisation avec un cutoff et des techniques de régularisation dimensionnelle sont analysées et appliquées. Dans le cas de la régularisation dimensionnelle, des connexions sont naturellement établies entre le cadre EDF et des techniques employées dans les théories de champ effectives. Dans la deuxième partie de la thèse, nous vérifions si les interactions régularisées introduites pour la matière nucléaire peuvent être utilisées également pour les noyaux finis. A titre d'illustration, cette analyse est effectuée dans le modèle de couplage particule vibration, qui représente un exemple de modèle qui va au-delà de l'approximation de champ moyen, où une divergence ultraviolette apparaît si des forces de portée nulle sont utilisées. Ces premières applications suggèrent plusieurs directions à explorer pour fournir à plus long terme des interactions régularisées qui sont bien adaptés pour les calculs au-delà du champ moyen pour les noyaux finis. Les conclusions et des perspectives sont illustrées à la fin du manuscrit. / Mean-field approaches successfully reproduce nuclear bulk properties like masses and radii within the Energy Density Functional (EDF) framework. However, complex correlations are missing in mean-field theories and several observables related to single-particle and collective nuclear properties cannot be predicted accurately. The necessity to provide a precise description of the available data as well as reliable predictions in the exotic regions of the nuclear chart motivates the use of more sophisticated beyond-mean-field models. Correlations and higher-order corrections (beyond the leading mean-field order) are introduced. A crucial aspect in these calculations is the choice of the effective interaction to be used when one goes beyond the leading order (available effective interactions are commonly adjusted at the mean-field level). In the first part, we deal with the equation of state of nuclear matter evaluated up to the second order with the phenomenological Skyrme force. We analyze the ultraviolet divergence that is related to the zero range of the interaction and we introduce Skyrme-type regularized interactions that can be used at second order for matter. Cutoff regularization and dimensional regularization techniques are explored and applied. In the latter case, connections are naturally established between the EDF framework and some techniques employed in Effective Field Theories. In the second part, we check whether the regularized interactions introduced for nuclear matter can be employed also for finite nuclei. As an illustration, this analysis is performed within the particle-vibration model that represents an example of beyond mean-field models where an ultraviolet divergence appears if zero-range forces are used. These first applications suggest several directions to be explored to finally provide regularized interactions that are specially tailored for beyond-mean-field calculations for finite nuclei. Conclusions and perspectives are finally illustrated.
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Bilingvismus ve vztahu k závislosti na poli / Bilingualism in relation to the field dependenceVoldánová, Petra January 2019 (has links)
The present diploma thesis focuses on the relation of the bilingualism and the cognitive style of field dependence/independence. Its first theoretical chapter deals with the issue of cognitive styles, in particular field dependence/independence, its history, possibilities of testing, namely the Embedded Figures Test and its group and online modifications. The second chapter of the theoretical part provides a characteristics and description of the phenomenon of bilingualism, its classification and a review of selected studies of bilingualism in relation to cognitive abilities and with the concept of field (in)dependence. During the former researches, higher tendency to the field-independence in youth non-adult bilinguals was proved. The purpose of the empirical part of this thesis aims to find, using the Online Group Embedded Figures Test, if the bilinguals still differ in this higher tendency from monolinguals in the adulthood. Based on the sample of 30 adult individual natural bilinguals, whose results in the Online GEFT test were compared to the results of 30 adult monolinguals in the same test, a statistically significant difference was not proved. From this result we can claim, that in adulthood, the difference of the field-independence between bilingual and monolingual population tends to...
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Legal and regulatory aspects of mobile financial servicesPerlman, Leon Joseph 11 1900 (has links)
The thesis deals with the emergence of bank and non-bank entities that provide a range of unique
transaction-based payment services broadly called Mobile Financial Services (MFS) to unbanked,
underserved and underbanked persons via mobile phones.
Models of MFS from Mobile Network Operators (MNOs), banks, combinations of MNOs and banks, and
independent Mobile Financial Services Providers are covered. Provision by non-banks of ‘bank-type’
services via mobile phones has been termed ‘transformational banking’ versus the ‘additive banking’
services from banks. All involve the concept of ‘branchless banking’ whereby ‘cash-in/cash out’ services
are provided through ‘agents.’
Funds for MFS payments may available through a Stored Value Product (SVP), particularly through a
Stored Value Account SVP variant offered by MNOs where value is stored as a redeemable fiat- or mobile
‘airtime’-based Store of Value.
The competitive, legal, technical and regulatory nature of non-bank versus bank MFS models is discussed,
in particular the impact of banking, payments, money laundering, telecommunications, e-commerce and
consumer protection laws. Whether funding mechanisms for SVPs may amount to deposit-taking such that
entities could be engaged in the ‘business of banking’ is discussed. The continued use of ‘deposit’ as the
traditional trigger for the ‘business of banking’ is investigated, alongside whether transaction and paymentcentric
MFS rises to the ‘business of banking.’
An extensive evaluation of ‘money’ based on the Orthodox and Claim School economic theories is
undertaken in relation to SVPs used in MFS, their legal associations and import, and whether they may be
deemed ‘money’ in law.
Consumer protection for MFS and payments generally through current statute, contract, and payment law
and common law condictiones are found to be wanting. Possible regulatory arbitrage in relation to MFS in
South African law is discussed.
The legal and regulatory regimes in the European Union, Kenya and the United States of America are
compared with South Africa. The need for a coordinated payments-specific law that has consumer
protections, enables proportional risk-based licensing of new non-bank providers of MFS, and allows for a
regulator for retail payments is recommended. The use of trust companies and trust accounts is
recommended for protection of user funds.
| vi / Public, Constitutional and International Law / LLD
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Legal and regulatory aspects of mobile financial servicesPerlman, Leon Joseph 11 1900 (has links)
The thesis deals with the emergence of bank and non-bank entities that provide a range of unique
transaction-based payment services broadly called Mobile Financial Services (MFS) to unbanked,
underserved and underbanked persons via mobile phones.
Models of MFS from Mobile Network Operators (MNOs), banks, combinations of MNOs and banks, and
independent Mobile Financial Services Providers are covered. Provision by non-banks of ‘bank-type’
services via mobile phones has been termed ‘transformational banking’ versus the ‘additive banking’
services from banks. All involve the concept of ‘branchless banking’ whereby ‘cash-in/cash out’ services
are provided through ‘agents.’
Funds for MFS payments may available through a Stored Value Product (SVP), particularly through a
Stored Value Account SVP variant offered by MNOs where value is stored as a redeemable fiat- or mobile
‘airtime’-based Store of Value.
The competitive, legal, technical and regulatory nature of non-bank versus bank MFS models is discussed,
in particular the impact of banking, payments, money laundering, telecommunications, e-commerce and
consumer protection laws. Whether funding mechanisms for SVPs may amount to deposit-taking such that
entities could be engaged in the ‘business of banking’ is discussed. The continued use of ‘deposit’ as the
traditional trigger for the ‘business of banking’ is investigated, alongside whether transaction and paymentcentric
MFS rises to the ‘business of banking.’
An extensive evaluation of ‘money’ based on the Orthodox and Claim School economic theories is
undertaken in relation to SVPs used in MFS, their legal associations and import, and whether they may be
deemed ‘money’ in law.
Consumer protection for MFS and payments generally through current statute, contract, and payment law
and common law condictiones are found to be wanting. Possible regulatory arbitrage in relation to MFS in
South African law is discussed.
The legal and regulatory regimes in the European Union, Kenya and the United States of America are
compared with South Africa. The need for a coordinated payments-specific law that has consumer
protections, enables proportional risk-based licensing of new non-bank providers of MFS, and allows for a
regulator for retail payments is recommended. The use of trust companies and trust accounts is
recommended for protection of user funds.
| vi / Public, Constitutional and International Law / LL. D.
|
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