The Conformal Anomaly in General Rank 1 Symmetric Spaces and Associated Operator Product

We compute the one-loop effective action and the conformal anomaly associated with the product $\bigotimes_p{\cal L}_p$ of the Laplace type operators ${\cal L}_p, p=1,2$, acting in irreducible rank 1 symmetric spaces of non-compact type. The explicit form of the zeta functions and the conformal anomaly of the stress-energy momentum tensor is derived.Comment: 10 pages, LaTe

Considerações sobre a política externa brasileira no governo Bolsonaro e as relações EUA-Brasil

O governo brasileiro de Jair Bolsonaro inaugurou inédita direção de política externa: movida exclusivamente por motivações ideológicas, sem compromisso com qualquer concepção de interesses nacionais. A ausência deste norte fundamental, que traz, entre outras consequências, uma adesão excessiva, quase totalmente automática e acrítica às decisões e políticas dos Estados Unidos de Donald Trump, coloca o Brasil em posição de grande desvantagem e insegurança em diferentes âmbitos do plano internacional. Expõe, ainda, a incapacidade da atual política externa de lidar com desafios e obstáculos de um sistema internacional que caminha a passos largos para uma transformação estrutural profunda neste século XXI. Nesse sentido, este artigo, de natureza quase ensaística, propõe-se a inventariar o conjunto de ações e medidas adotadas até o momento pela política externa da gestão Bolsonaro (ex-PSL, atual Aliança pelo Brasil), especialmente no que se refere a Washington, usando-as como base de sustentação dos argumentos expostos acima

Forms on Vector Bundles Over Compact Real Hyperbolic Manifolds

We study gauge theories based on abelian $p-$ forms on real compact hyperbolic manifolds. The tensor kernel trace formula and the spectral functions associated with free generalized gauge fields are analyzed.Comment: Int. Journ. Modern Physics A, vol. 18 (2003), 2041-205

MHD numerical simulations of colliding winds in massive binary systems - I. Thermal vs non-thermal radio emission

In the past few decades detailed observations of radio and X-rays emission from massive binary systems revealed a whole new physics present in such systems. Both thermal and non-thermal components of this emission indicate that most of the radiation at these bands originates in shocks. OB and WR stars present supersonic and massive winds that, when colliding, emit largely due to the free-free radiation. The non-thermal radio and X-ray emissions are due to synchrotron and inverse compton processes, respectively. In this case, magnetic fields are expected to play an important role on the emission distribution. In the past few years the modeling of the free-free and synchrotron emissions from massive binary systems have been based on purely hydrodynamical simulations, and ad hoc assumptions regarding the distribution of magnetic energy and the field geometry. In this work we provide the first full MHD numerical simulations of wind-wind collision in massive binary systems. We study the free-free emission characterizing its dependence on the stellar and orbital parameters. We also study self-consistently the evolution of the magnetic field at the shock region, obtaining also the synchrotron energy distribution integrated along different lines of sight. We show that the magnetic field in the shocks is larger than that obtained when the proportionality between $B$ and the plasma density is assumed. Also, we show that the role of the synchrotron emission relative to the total radio emission has been underestimated.Comment: MNRAS accepte

As relações luso-brasileiras nos anos 1950

In this paper I analyse Brazil-Portugal relations from WWII until the mid-1960s. The apex of [their] diplomatic teamwork occurred during the Kubitschek government (1956-1961). Portugal ’s effort to keep its Asian and African colonies is the main analytic key explaining the intensity of these bilateral relations.Neste texto, analiso as relações Brasil-Portugal entre a Segunda Guerra Mundial até meados da década de 1960. O ápice do entrosamento diplomático deu-se durante o governo Kubitschek (1956-1961). O esforço despendido por Portugal com vistas a manter suas colônias asiáticas e africanas é a principal chave analítica para explicar a intensidade dessas relações bilaterais

Reflexões sobre a nova ordem internacional pós-pandemia

Este texto se insere na discussão sobre a mudança na ordem internacional. Em primeiro lugar, busca definir ordem internacional e identificar os traços fundamentais do conceito. Em seguida, examina como, ao longo da história, a ordem internacional tem evoluído. A seguir, o texto discute as razões pelas quais a questão da mudança da ordem internacional figura como incontornável. E, por fim, discute também o que, em virtude do que se considera o traço nuclear da ideia, pode tornar uma nova ordem internacional diferente daquelas historicamente conhecida

Osteochondral Tissue Engineering: The Potential of Electrospinning and Additive Manufacturing

The socioeconomic impact of osteochondral (OC) damage has been increasing steadily over time in the global population, and the promise of tissue engineering in generating biomimetic tissues replicating the physiological OC environment and architecture has been falling short of its projected potential. The most recent advances in OC tissue engineering are summarised in this work, with a focus on electrospun and 3D printed biomaterials combined with stem cells and biochemical stimuli, to identify what is causing this pitfall between the bench and the patients' bedside. Even though significant progress has been achieved in electrospinning, 3D-(bio)printing, and induced pluripotent stem cell (iPSC) technologies, it is still challenging to artificially emulate the OC interface and achieve complete regeneration of bone and cartilage tissues. Their intricate architecture and the need for tight spatiotemporal control of cellular and biochemical cues hinder the attainment of long-term functional integration of tissue-engineered constructs. Moreover, this complexity and the high variability in experimental conditions used in different studies undermine the scalability and reproducibility of prospective regenerative medicine solutions. It is clear that further development of standardised, integrative, and economically viable methods regarding scaffold production, cell selection, and additional biochemical and biomechanical stimulation is likely to be the key to accelerate the clinical translation and fill the gap in OC treatment

Photoproduction at the Relativistic Heavy Ion Collider with STAR

The strong electromagnetic fields of short duration associated with relativistic heavy ions make a heavy-ion collider a unique tool to study two-photon and photonuclear collisions. In this talk, we introduce the principles of photoproduction at hadron colliders, review recent results from RHIC on meson and e$^+$e$^-$ production. At RHIC, STAR has studied exclusive $\rho^{0}$ vector meson production and $\rho^{0}$ production accompanied by electromagnetic dissociation of both nuclei in collisions of AuAu at 62, 130 and 200 GeV. Recent results suggest the validity of the Glauber calculations for the vector meson photoproduction and incosistency of the model based on the parton saturation phenomenon. The measurements are a lso sensitive to interference between production on the two nuclei: either ion can be the photon emitter or the target. The level of observed interference suggests that the final state wave function carries information about all possible decays long after the decay occurs. We also observe coherent photoproduction of a $\pi ^{+}\pi^{-}\pi^{+}\pi^{-}$ state which may be associated with $\rho^{0*}$ (1450).Comment: 4 pages 2 figures - To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennesse