Asteroseismic Theory of Rapidly Oscillating Ap Stars

This paper reviews some of the important advances made over the last decade concerning theory of roAp stars.Comment: 9 pages, 5 figure

Impact of micro-telluric lines on precise radial velocities and its correction

Context: In the near future, new instruments such as ESPRESSO will arrive, allowing us to reach a precision in radial-velocity measurements on the order of 10 cm/s. At this level of precision, several noise sources that until now have been outweighed by photon noise will start to contribute significantly to the error budget. The telluric lines that are not neglected by the masks for the radial velocity computation, here called micro-telluric lines, are one such noise source. Aims: In this work we investigate the impact of micro-telluric lines in the radial velocities calculations. We also investigate how to correct the effect of these atmospheric lines on radial velocities. Methods: The work presented here follows two parallel lines. First, we calculated the impact of the micro-telluric lines by multiplying a synthetic solar-like stellar spectrum by synthetic atmospheric spectra and evaluated the effect created by the presence of the telluric lines. Then, we divided HARPS spectra by synthetic atmospheric spectra to correct for its presence on real data and calculated the radial velocity on the corrected spectra. When doing so, one considers two atmospheric models for the synthetic atmospheric spectra: the LBLRTM and TAPAS. Results: We find that the micro-telluric lines can induce an impact on the radial velocities calculation that can already be close to the current precision achieved with HARPS, and so its effect should not be neglected, especially for future instruments such as ESPRESSO. Moreover, we find that the micro-telluric lines' impact depends on factors, such as the radial velocity of the star, airmass, relative humidity, and the barycentric Earth radial velocity projected along the line of sight at the time of the observation.Comment: Accepted in A&

ANALYSIS OF CESAREAN SECTION RATES AND INDICATIONS USING TEN GROUP CLASSIFICATION

Introdução e objetivo: Foi efetuado um estudo observacional retrospetivo para analisar os motivos de cesariana e identificar os parâmetros obstétricos das mulheres a ela submetidas na nossa instituição em janeiro/fevereiro e junho/julho de 2011. Material e Métodos: Foram revistos os processos clínicos destas mulheres, categorizadas nos dez grupos obstétricos propostos por Robson, baseados nos seguintes parâmetros: gestação simples/múltipla; nuliparidade/multiparidade/multiparidade com cesariana anterior, cefálico/não-cefálico; parto espontâneo/ induzido/cesariana eletiva; parto de termo/pré-termo. Em cada grupo foram analisados os motivos de cesariana excepto os das gestações múltiplas. Resultados: Ocorreram 1167 partos simples, 391 por cesariana, sendo a taxa de cesarianas 33,5% (36% eletivas). A cesariana foi mais frequente em nulíparas de termo com parto induzido e em mulheres com cesariana prévia. Durante o trabalho de parto o motivo mais comum nomeado pelo clínico foi o trabalho de parto estacionário, a incompatibilidade feto-pélvica e o estado fetal não tranquilizador. A apresentação fetal anómala motivou 4,4% da taxa de cesarianas, contributo superior ao da prematuridade (3%). Entre as multíparas de termo sem cicatriz uterina houve menor número de cesarianas. Conclusões: A análise dos resultados obtidos sugere que evitar uma primeira cesariana e permitir o início espontâneo do trabalho de parto pode contribuir para o decréscimo a longo prazo da taxa de cesarianas. É fundamental um esforço coletivo para objetivar as suas indicações e que estas reflitam as orientações mais atualizadas relativas ao estado fetal não tranquilizador e ao trabalho de parto estacionário

Quantum computing with incoherent resources and quantum jumps

Spontaneous emission and the inelastic scattering of photons are two natural processes usually associated with decoherence and the reduction in the capacity to process quantum information. Here we show that when suitably detected, these photons are sufficient to build all the fundamental blocks needed to perform quantum computation in the emitting qubits while protecting them from deleterious dissipative effects. We exemplify by showing how to teleport an unknown quantum state and how to efficiently prepare graph states for the implementation of measurement-based quantum computation.Comment: 5 pages, 5 figure

ATP is released from nerve terminals and from activated muscle fibres on stimulation of the rat phrenic nerve

Nerve stimulation increases the concentration of ATP in the synaptic cleft, which can act as a neurotransmitter or as a presynaptic neuromodulator. Using the luciferin-luciferase assay, we observed that the extracellular concentration of ATP increased by 11-26 nM over a basal concentration of 6 nM, in a frequency dependent manner (1-5 Hz), in the adult rat phrenic nerve-hemidiaphragm preparation. This ATP release depends on nerve activity since it was abolished by tetrodotoxin (1 [mu]M) and is strictly dependent on the presence of extracellular calcium. However, more than half of this nerve-evoked release of ATP is derived from activated muscle fibres since the selective post-synaptic nicotinic receptor antagonist, [alpha]-bungarotoxin (1 [mu]M), inhibited by over 60% the evoked release of ATP. The presently observed post-synaptic release of ATP together with the previously reported lack of post-synaptic effects of ATP and to the ability of ATP to act as a presynaptic modulator open the possibility that ATP may behave as a retrograde messenger at this neuromuscular junction.http://www.sciencedirect.com/science/article/B6T0G-47S6YPN-X/1/e09fe63a6ed4383fc2ed5996ece6ac4