Pictor A (PKS 0518-45) - From Nucleus to Lobes

We present radio and optical imaging and kinematic data for the radio galaxy Pictor A, including HST continuum and [OIII], emission-line images (at a resolution of 25 - 100 mas) and ground-based imaging and spectroscopy (at a resolution of ~ 1.5". The radio data include 3 cm Australia Telescope images of the core, at a resolution comparable to that of the optical, ground-based images, and a VLBI image of a jet in the compact core (at a resolution of 2 - 25 mas), which seems to align with a continuum ``jet'' found in the HST images. The core radio jet, the HST optical continuum ``jet'', and the NW H-alpha filaments all appear to point toward the optical-synchrotron hot-spot in the NW lobe of this object and are associated with a disrupted velocity field in the extended ionized gas. The ground-based spectra which cover this trajectory also yield line ratios for the ionized gas which have anomalously low [NII] (6564), suggesting either a complex, clumpy structure in the gas with a higher cloud-covering factor at larger radii and with denser clouds than is found in the nuclear regions of most NLRG and Seyfert 2 galaxies, or some other, unmodeled, mechanism for the emergent spectrum from this region. The H-alpha emission-line filaments to the N appear to be associated with a 3 cm radio continuum knot which lies in a gap in the filaments ~ 4" from the nucleus. Altogether, the data in this paper provide good circumstantial evidence for non-disruptive redirection of a radio jet by interstellar gas clouds in the host galaxy.Comment: 19 pages, 6 ps.gz fig pages, to appear in the Ap.J. Supp

Extracellular electrical signals in a neuron-surface junction: model of heterogeneous membrane conductivity

Signals recorded from neurons with extracellular planar sensors have a wide range of waveforms and amplitudes. This variety is a result of different physical conditions affecting the ion currents through a cellular membrane. The transmembrane currents are often considered by macroscopic membrane models as essentially a homogeneous process. However, this assumption is doubtful, since ions move through ion channels, which are scattered within the membrane. Accounting for this fact, the present work proposes a theoretical model of heterogeneous membrane conductivity. The model is based on the hypothesis that both potential and charge are distributed inhomogeneously on the membrane surface, concentrated near channel pores, as the direct consequence of the inhomogeneous transmembrane current. A system of continuity equations having non-stationary and quasi-stationary forms expresses this fact mathematically. The present work performs mathematical analysis of the proposed equations, following by the synthesis of the equivalent electric element of a heterogeneous membrane current. This element is further used to construct a model of the cell-surface electric junction in a form of the equivalent electrical circuit. After that a study of how the heterogeneous membrane conductivity affects parameters of the extracellular electrical signal is performed. As the result it was found that variation of the passive characteristics of the cell-surface junction, conductivity of the cleft and the cleft height, could lead to different shapes of the extracellular signals

Local control in metastatic neuroblastoma in children over 1 year of age

Background: Local control is always considered in metastatic neuroblastoma (NBL). The aim of this study is to evaluate the impact of radical surgery on survival in children over 1 year of age. Methods: Fifty-eight patients older than 1 year of age with metastatic NBL were treated with conventional plus high-dose chemotherapy with or without addition of local radiotherapy (RT, 21Gy). Surgery was classified as radical surgery (complete resection and gross total resection) or non-radical surgery. The Kaplan-Meier method and the Cox proportional hazard model were used to calculate the probability of progression free and overall survival (PFS and OS) and for multivariate analysis. Results: The 5-year PFS and OS for patients with radical surgery were 26% (95% CI 14-40%) and 38% (95% CI 23-53%) respectively, while the PFS and OS for patients without radical surgery were 33% (95% CI 10-59%) and 31% (95% CI 10-55%) (respectively, P 0.85 and P 0.42). The 5-year PFS and OS for patients who received RT were 36% (95% CI 19-53%) and 46% (95% CI 26-64%) respectively, while the 5-year PFS and OS for patients who did not receive RT were 22% (95% CI 9-38%) and 27% (95% CI 13-42%) respectively (P 0.02 for PFS). Multivariate analysis confirmed the role of well-known prognostic factors, such as the presence of MYCN amplification, age and response before high-dose chemotherapy. Conclusions: Our data suggest that the degree of resection does not influence survival in metastatic NBL patients treated with high-dose chemotherapy; local RT contributes to local disease control

Rheoencephalographic observations in migraine

The pathophysiological concept of migraine presently held attributes the major changes to vascular factors. Therefore, it seemed appropriate to use rheoencephalography to test cerebral hemodynamics in cases of migraine. This very harmless and well suited method revealed: (1) on routine tracings during the painless intervall only 1/7 of the cases showed significant changes, while more than 2/3 could be classified with the help of an orthostatic stress test under REG-observation; (2) REG is more often correct for diagnosis than EEG and this does not surprise since REG monitors cerebral hemodynamics directly while EEG records activity for parenchyma and thus only secondarily depends on circulation; (3) similar conditions were previously seen in Meniere's disease where EEG also is less efficient than REG. According to the results of this study, it should be interesting to include REG in the work-up of migrainous patients. In these and under similar conditions, REG will be of diagnostic value

Rheoencephalographic observations in migraine Reoencefalografia: observações na enxaqueca

The pathophysiological concept of migraine presently held attributes the major changes to vascular factors. Therefore, it seemed appropriate to use rheoencephalography to test cerebral hemodynamics in cases of migraine. This very harmless and well suited method revealed: (1) on routine tracings during the painless intervall only 1/7 of the cases showed significant changes, while more than 2/3 could be classified with the help of an orthostatic stress test under REG-observation; (2) REG is more often correct for diagnosis than EEG and this does not surprise since REG monitors cerebral hemodynamics directly while EEG records activity for parenchyma and thus only secondarily depends on circulation; (3) similar conditions were previously seen in Meniere's disease where EEG also is less efficient than REG. According to the results of this study, it should be interesting to include REG in the work-up of migrainous patients. In these and under similar conditions, REG will be of diagnostic value.No conceito fisiopatológico da enxaqueca atribui-se grande importância às alterações vasculares. Por esta razão empregamos a reoencefalografia, método simples e inócuo que nos pareceu o mais adequado para estudar a hemodinâmica cerebral em casos de hemicrania. Nossas conclusões foram as seguintes: (1) nos traçados reoencefalográficos de rotina encontramos, em apenas 1/7 dos casos, alterações qualitativas e quantitivas significantes no período intercrítico da enxaqueca, ao passo que mais de 2/3 dos traçados podiam ser classificados como patológicos e característicos, desde que utilizássemos o teste ortostático de Schellong; (2) a reoencefalografia parece ser mais precisa do que a eletrencefalografia para o diagnóstico de hemicrania; este fato é compreensível pois o reoencefalograma registra diretamente a hemodinâmica cerebral, enquanto que o eletrencefalograma registra a atividade bioelétrica do parênquima a qual, por sua vez, apenas secundariamente depende de circulação sangüínea; (3) resultados semelhantes foram, também, observados em casos de síndrome de Menière nos quais a eletrencefalografia seria, também, menos útil que a reoencefalografia. De acordo com estes resultados, parece-nos ser lícito sugerir a inclusão la reoencefalografia na rotina e no controle terapêutico de pacientes com íemicrânia. Nesta e em outras condições similares a reoencefalografia é im método paraclínico de alto valor