Cell replacement therapy in Parkinson's disease (PD) aims at re-establishing dopamine neurotransmission in the striatum by grafting dopamine-releasing cells. Chromaffin cell (CC) grafts produce some transitory improvements of functional motor deficits in PD animal models, and have the advantage of allowing autologous transplantation. However, CC grafts have exhibited low survival, poor function...

We present a comparative analysis of the chromospheric solar limb prolateness, using strictly simultaneous Hα ground-based observations and HeII space-based observations. The typical prolateness is found to be ∆D/D = 5.5 × 10−3 in HeII and 1.2 × 10−3 in Hα. The first measurements in the 30.4 nm HeII line over a period of two years, as well as coronal data, are discussed to explore further the o...

Context. High spectral resolution X-ray observations of classical T Tauri stars (CTTSs) demonstrate the presence of plasma at T ∼ 2−3×106 K and ne ∼ 1011−1013 cm−3, unobserved in non-accreting stars. Stationary models suggest that this emission is due to shockheated accreting material, but they do not allow to analyze the stability of such material and its position in the stellar atmosphere. Ai...

Received ; accepted – 2 – ABSTRACT We investigate the structure of the solar chromosphere and transition region using full Sun images obtained with the Extreme Ultraviolet Imaging Telescope (EIT) aboard the Solar and Heliospheric Observatory (SOHO) spacecraft. The limb seen in the EIT coronal images (taken in lines of Fe IX/X at 171Å, Fe XII at 195Å and Fe XV at 284Å) is an absorption limb pred...

Alfvén wave propagation, reflection, and heating of the chromosphere are studied for a one-dimensional solar atmosphere by self-consistently solving plasma, neutral fluid, and Maxwell’s equations with incorporation of the Hall effect and strong electron–neutral, electron–ion, and ion–neutral collisions. We have developed a numerical model based on an implicit backward difference formula of seco...

We study the acoustic properties of the solar chromosphere in the high-frequency regime using a time sequence of velocity measurements in the chromospheric Ca II 854.2 nm line taken with the Interferometric Bidimensional Spectrometer (IBIS). We concentrate on quiet-Sun behavior, apply Fourier analysis, and characterize the observations in terms of the probability density functions (PDFs) of vel...

Three-dimensional numerical simulations with COBOLD, a new radiation hydrodynamics code, result in a dynamic, thermally bifurcated model of the non-magnetic chromosphere of the quiet Sun. The 3-D model includes the middle and low chromosphere, the photosphere, and the top of the convection zone, where acoustic waves are excited by convective motions. While the waves propagate upwards, they stee...

The Hubble Space Telescope observed red supergiant Betelgeuse (αOri) with the Space Telescope Imaging Spectrograph to investigate the outer atmosphere from spatially resolved spectra. We present a new set of seven highresolution near-UV spectra observed with HST-STIS in fall 2002 and spring 2003, by scanning at chromospheric intensity peak-up position and six off-limb target positions up to thr...

The chromosphere (the link between the photosphere and the corona) plays a crucial role in flare and CME development. In analogies between flares and magnetic substorms, it is normally identified with the ionosphere, but we argue that the correspondence is not exact. Much of the important physics of this interesting region remains to be explored. We discuss chromospheric flares in the context o...

Aims. We investigate the relationship between the photospheric magnetic field and the emission of the mid chromosphere of