On the relationship of the scaled phase space and Skyrme-coherent state treatments of proton antiproton annihilation at rest

We discuss pion multiplicities and single pion momentum spectra from proton antiproton annihilation at rest. Both the scaled phase space model and the Skyrme-coherent state approach describe these observables well. In the coherent state approach the puzzling size of the scale parameter relating the phase space integrals for different multiplicities is replaced by a well defined weight function. The strength of this function is determined by the intensity of the classical pion field and its spatial extent is of order 1 fm.Comment: 11 pages including 4 figures(postscript

Circularly Polarized Resonant Rayleigh Scattering and Skyrmions in the ν\nu = 1 Quantum Hall Ferromagnet

We use the circularly polarized resonant Rayleigh scattering (RRS) to study the quantum Hall ferromagnet at $\nu$ = 1. At this filling factor we observe a right handed copolarized RRS which probes the Skyrmion spin texture of the electrons in the photoexcited grounds state. The resonant scattering is not present in the left handed copolarization, and this can be related to the correlation between Skymionic effects, screening and spin wave excitations. These results evidence that RRS is a valid method for the study of the spin texture of the quantum Hall states

Tattoos on Instagram : how the platform connects professionals and consumers

The object of study of this dissertation is the relationship created through Instagram between tattoo artists and consumers. This investigation emphasizes how the relationship allows artists to position themselves in this social network, its advantages, and the reasons that lead a consumer to get a tattoo. The relevance of the same is because few studies investigate the consumption of tattoos in Portugal, the connection that followers create on Instagram with tattoo artists and the impact that this has on the consumption of tattoos. As for the methodological choice, it is a mixed study. That involved the qualitative analysis of the data collected from content analysis and interviews with 6 tattoo artists, as well as the quantitative analysis of the data collected from a questionnaire answered by 567 tattoo consumers on Instagram. It is concluded that tattoo artists connect with their followers on Instagram by sharing personal content that allows identification by consumers. The reasons for consumers to follow tattoo artists are entertainment search and identification, and they interact with them mainly through private messages, answering polls on Instagram stories, comments and likes.O objeto de estudo desta dissertação é a relação criada através do Instagram entre tatuadores e consumidores. Esta investigação explora como a relação permite que os artistas se posicionem nesta rede social, as vantagens que a mesma tem e quais as razões que levam um consumidor marcar uma tatuagem. A pertinência da mesma é justificada por serem poucos os estudos que investigam o consumo de tatuagens em Portugal, sobre a conexão que seguidores criam no Instagram com os tatuadores e o impacto que isso causa no consumo de tatuagens. Quanto à escolha metodológica, trata-se de um estudo misto. Este envolveu a análise qualitativa dos dados recolhidos a partir de uma analise conteúdo e entrevistas feitas a 6 tatuadores, bem como a análise quantitativa dos dados recolhidos a partir de um questionário respondido por 567 consumidores. Conclui-se que os tatuadores conectam-se com seus seguidores no Instagram através da partilha de conteúdo pessoal que permite uma identificação por parte dos consumidores. As razões para os consumidores seguirem os tatuadores são a busca de entretenimento e a identificação, sendo que interagem com os mesmos principalmente através de mensagens privadas, responder a sondagens nas histórias do Instagram, comentários e gostos

Online Shopping Behaviours during quarantine: Zara case study

Dissertation presented as the partial requirement for obtaining a Master's degree in Information Management, specialization in Marketing IntelligenceNowadays, due to the phenomenon of globalization and technological evolution, the offer of goods and services has been growing exponentially and, consequently, consumers have more and more brands at their disposal. Naturally, this evolution has had a huge impact on the growth of online commerce. Virtually all industries have adopted online commerce, giving consumers the possibility to buy their products/services online, through computers or smartphones, without having physically to go to a store. The fashion industry is no exception and increasingly invests in e-commerce to optimize the consumer experience. Brands have the ability to offer services that serve as an extension of the communication carried out in physical stores, therefore complementing the consumer's experience so that it becomes more real and satisfying. This type of commerce also allows the brands to better understand the customer needs and the major market trends, providing an increasingly satisfying consumer experience. This dissertation intends to analyse the behaviours and relationships underlying online shopping by understanding what drives consumers to buy online instead of going to a store. I chose the Zara brand as the object of my study, not only because it is a brand with a lot of notoriety in the world market, but also because it has an extremely important position and relevance in the Portuguese market. The conclusions and results of this study demonstrate that the tendency is towards online shopping. Through the quantitative analysis of the results obtained, it is possible to verify that Covid19 has increased the online purchases, however people are not very afraid of going shopping in person. They seem to choose the online option due to its comfort and efficiency. It is also discussed the importance of creating bonds between consumers and the brands since these relationships are later translated into profitability and growth for the companies

Searching for δ\delta Scuti-type pulsation and characterising northern pre-main-sequence field stars

A photometric variability study of a sample of northern field stars, which previously classified as either PMS or Herbig Ae/Be objects, has been undertaken with the purpose of detecting {\delta} Scuti-type pulsations. Determination of physical parameters for these stars has also been carried out to locate them on the HR diagram and check the instability strip for this type of pulsators. Multichannel photomultiplier and CCD time series photometry in the uvby Str\"omgren and BVI Johnson bands were obtained during four consecutive years from 2007 to 2010. The light curves have been analysed, and a variability criterion has been established. Among the objects classified as variable stars, we have selected those which present periodicities above 4 d^(-1), which was established as the lowest limit for {\delta} Scuti-type pulsations in this investigation. Finally, these variable stars have been placed in a colour-magnitude diagram using the physical parameters derived with the collected uvby{\beta} Str\"omgren-Crawford photometry. Five PMS {\delta} Scuti- and three probable {\beta} Cephei-type stars have been detected. Two additional PMS {\delta} Scuti stars are also confirmed in this work. Moreover, three new {\delta} Scuti- and two {\gamma} Doradus-type stars have been detected among the main-sequence objects used as comparison or check stars.Comment: Accepted for publication in Section 14. Catalogs and data of Astronomy and Astrophysics. The official date of acceptance is 17/06/2014. 12 pages, 4 figures and 8 table

Plateau insulator transition in graphene

The quantum Hall effect in a single-layer graphene sample is studied in strong magnetic fields up to 28 T. Our measurements reveal the existence of a metal- insulator transition from filling factor $\nu=-2$ to $\nu=0$. The value of the universal scaling exponent is found to be $\kappa=0.57$ in graphene and therefore in a truly two-dimensional system. This value of $\kappa$ is in agreement with the accepted universal value for the plateau-insulator transitions in standard quasi two-dimensional electron and hole gases.Comment: 10 pages, 5 figure

Matrix Hamiltonians: SUSY approach to hidden symmetries

A new supersymmetric approach to the analysis of dynamical symmetries for matrix quantum systems is presented. Contrary to standard one dimensional quantum mechanics where there is no role for an additional symmetry due to nondegeneracy, matrix hamiltonians allow for non-trivial residual symmetries. This approach is based on a generalization of the intertwining relations familiar in SUSY Quantum Mechanics. The corresponding matrix supercharges, of first or of second order in derivatives, lead to an algebra which incorporates an additional block diagonal differential matrix operator (referred to as a "hidden" symmetry operator) found to commute with the superhamiltonian. We discuss some physical interpretations of such dynamical systems in terms of spin 1/2 particle in a magnetic field or in terms of coupled channel problem. Particular attention is paid to the case of transparent matrix potentials.Comment: 20 pages, LaTe