Biaxial nematic phase in the Maier-Saupe model for a mixture of discs and cylinders

We analyze the global phase diagram of a Maier-Saupe lattice model with the inclusion of disorder degrees of freedom to mimic a mixture of oblate and prolate molecules (discs and cylinders). In the neighborhood of a Landau multicritical point, solutions of the statistical problem can be written as a Landau-de Gennes expansion for the free energy. If the disorder degrees of freedom are quenched, we confirm the existence of a biaxial nematic strucure. If orientational and disorder degrees of freedom are allowed to thermalize, this biaxial solution becomes thermodynamically unstable. Also, we use a two-temperature formalism to mimic the presence of two distinct relaxation times, and show that a slight departure from complete thermalization is enough to stabilize a biaxial nematic phase.Comment: 21 pages, 3 figure

Measurement of miniband parameters of a doped superlattice by photoluminescence in high magnetic fields

We have studied a 50/50\AA superlattice of GaAs/Al$_{0.21}$Ga$_{0.79}$As composition, modulation-doped with Si, to produce $n=1.4\times 10^{12}$ cm$^{-2}$ electrons per superlattice period. The modulation-doping was tailored to avoid the formation of Tamm states, and photoluminescence due to interband transitions from extended superlattice states was detected. By studying the effects of a quantizing magnetic field on the superlattice photoluminescence, the miniband energy width, the reduced effective mass of the electron-hole pair, and the band gap renormalization could be deduced.Comment: minor typing errors (minus sign in eq. (5)

Penile Involvement as Initial Manifestation of Henoch-Schönlein Purpura

info:eu-repo/semantics/publishedVersio

Ex-utero intrapartum treatment (or EXIT procedure) in a case of cervical linfangiona

Introdução: Fetos com diagnóstico pré-natal de malformações anatómicas envolvendo a face e/ou o pescoço estão em risco de obstrução das vias aéreas desde o pós-natal imediato. A programação de medidas periparto que previnam a compressão das vias aéreas, mantendo uma adequada circulação fetal, é fundamental no prognóstico. Caso Clínico: Feto com diagnóstico ecográfico, às 31 semanas de gestação, de volumosa massa cervical e facial, compatível com linfangioma quístico. O caso foi discutido em equipa multidisciplinar, tendo sido decidida a realização de cesariana associada ao procedimento EXIT às 39 semanas de gestação. Após exteriorização do polo cefálico, foi confirmada massa cervical e facial direita, sendo o feto sujeito a intubação oro-traqueal no primeiro minuto. Ao sexto dia de vida foi submetido a cirurgia, com excisão parcial da massa. Conclusão: O procedimento EXIT permite a manutenção de uma adequada oxigenação fetal enquanto se estabelece uma via aérea patente. Uma adequada coordenação da equipa multidisciplinar é fundamental para o êxito da técnic

Application of Super-Resolution and Advanced Quantitative Microscopy to the Spatio-Temporal Analysis of Influenza Virus Replication

With an estimated three to five million human cases annually and the potential to infect domestic and wild animal populations, influenza viruses are one of the greatest health and economic burdens to our society, and pose an ongoing threat of large-scale pandemics. Despite our knowledge of many important aspects of influenza virus biology, there is still much to learn about how influenza viruses replicate in infected cells, for instance, how they use entry receptors or exploit host cell trafficking pathways. These gaps in our knowledge are due, in part, to the difficulty of directly observing viruses in living cells. In recent years, advances in light microscopy, including super-resolution microscopy and single-molecule imaging, have enabled many viral replication steps to be visualised dynamically in living cells. In particular, the ability to track single virions and their components, in real time, now allows specific pathways to be interrogated, providing new insights to various aspects of the virus-host cell interaction. In this review, we discuss how state-of-the-art imaging technologies, notably quantitative live-cell and super-resolution microscopy, are providing new nanoscale and molecular insights into influenza virus replication and revealing new opportunities for developing antiviral strategies