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Localization of axonally transported 125I-wheat germ agglutinin beneath the plasma membrane of chick retinal ganglion cells.
The distribution of 125I-wheat germ agglutinin (WGA) transported by axons of chick retinal ganglion cells to layer d of the optic tectum was studied by electron microscopic autoradiography. We found that 52% of the radioactivity was located in axons and axon terminals in the contralateral optic tectum 22 h after intravitreal injection of affinity-purified 125I-WGA. Axons comprised 43% of the volume of layer d. Dendrites, glial cells, and neuron cell bodies contained 20%, 17%, and 3% of the label, whereas these structures comprised 24%, 21%, and 2% of the tissue volume, respectively. We also measured the distances between the autoradiographic silver grains and the plasma membranes of these profiles, and compared observed distributions of grains to theoretical distributions computed for band-shaped sources at various distances from the plasma membranes. This analysis revealed that the radioactive source within axons was distributed in a band of cytoplasm extending in from the plasma membrane a distance of 63 nm. Because WGA is known to bind to specific membrane glycoconjugates, we infer that at least some glycoconjugates may be concentrated within an annular region of cytoplasm just beneath the axonal plasma membrane after axoplasmic transport from the neuron cell body
KINETICS OF ROD OUTER SEGMENT RENEWAL IN THE DEVELOPING MOUSE RETINA
The kinetics of rod outer segment renewal in the developing retina have been investigated in C57BL/6J mice. Litters of mice were injected with [3H]amino acids at various ages and killed at progressively later time intervals. Plastic 1.5 µm sections of retina were studied by light microscope autoradiography. The rate of outer segment disk synthesis, as judged by labeled disk displacement away from the site of synthesis, is slightly greater than the adult level at 11–13 days of age; it rises to more than 1.6 times the adult rate between days 13 and 17, after which it falls to the adult level at 21–25 days. The rate of disk disposal, as measured by labeled disk movement toward the site of disposal, is less than 15% of the adult level at 11–13 days of age; it rises sharply to almost 70% of the adult level by days 13–15 and then more gradually approaches the adult rate. The net difference in rates of synthesis and disposal accounts for the rapid elongation of rod outer segments in the mouse between days 11 and 17 and the subsequent, more gradual elongation to the adult equilibrium length reached between days 19 and 25. The changing rate of outer segment disk synthesis characterizes the late stages of cytodifferentiation of the rod photoreceptor cells
Characterising the surface magnetic fields of T Tauri stars with high-resolution near-infrared spectroscopy
We aim to characterise the surface magnetic fields of a sample of 8 T Tauri
stars from high-resolution near-IR spectroscopy. Some stars in our sample are
known to be magnetic from previous spectroscopic or spectropolarimetric
studies. Our goals are 1) to apply Zeeman broadening modelling to T Tauri stars
with high-resolution data, 2) to expand the sample of stars with measured
surface magnetic field strengths, 3) to investigate possible rotational or
long-term magnetic variability by comparing spectral time series of given
targets, and 4) to compare the magnetic field modulus tracing small-scale
magnetic fields to those of large-scale magnetic fields derived by Stokes V
Zeeman Doppler Imaging. We modelled the Zeeman broadening of magnetically
sensitive spectral lines in the near-IR K-band from high-resolution spectra by
using magnetic spectrum synthesis based on realistic model atmospheres and by
using different descriptions of the surface magnetic field. We developped a
Bayesian framework that selects the complexity of the magnetic field
prescription based on the information contained in the data. We obtain
individual magnetic field measurements for each star in our sample using four
different models. We find that the Bayesian Model 4 performs best in the range
of magnetic fields measured on the sample (from 1.5 kG to 4.4 kG). We do not
detect a strong rotational variation of with a mean peak-to-peak variation
of 0.3 kG. Our confidence intervals are of the same order of magnitude, which
suggests that the Zeeman broadening is produced by a small-scale magnetic field
homogeneously distributed over stellar surfaces. A comparison of our results
with mean large-scale magnetic field measurements from Stokes V ZDI show
different fractions of mean field strength being recovered, from 25-42% for
relatively simple poloidal axisymmetric field topologies to 2-11% for more
complex fields.Comment: 14 pages, 9 figures, accepted for publication in Astronomy and
Astrophysic
Magnetic fields of intermediate mass T Tauri stars
Aims. In this paper, we aim to measure the strength of the surface magnetic
fields for a sample of five intermediate mass T Tauri stars and one low mass T
Tauri star from late-F to mid-K spectral types. While magnetic fields of T
Tauri stars at the low mass range have been extensively characterized, our work
complements previous studies towards the intermediate mass range; this
complementary study is key to evaluate how magnetic fields evolve during the
transition from a convective to a radiative core.
Methods. We studied the Zeeman broadening of magnetically sensitive spectral
lines in the H-band spectra obtained with the CRIRES high-resolution
near-infrared spectrometer. These data are modelled using magnetic spectral
synthesis and model atmospheres. Additional constraints on non-magnetic line
broadening mechanisms are obtained from modelling molecular lines in the K band
or atomic lines in the optical wavelength region.
Results. We detect and measure mean surface magnetic fields for five of the
six stars in our sample: CHXR 28, COUP 107, V2062 Oph, V1149 Sco, and Par 2441.
Magnetic field strengths inferred from the most magnetically sensitive
diagnostic line range from 0.8 to 1.8 kG. We also estimate a magnetic field
strength of 1.9 kG for COUP 107 from an alternative diagnostic. The magnetic
field on YLW 19 is the weakest in our sample and is marginally detected, with a
strength of 0.8 kG.
Conclusions. We populate an uncharted area of the pre-main-sequence HR
diagram with mean magnetic field measurements from high-resolution
near-infrared spectra. Our sample of intermediate mass T Tauri stars in general
exhibits weaker magnetic fields than their lower mass counterparts. Our
measurements will be used in combination with other spectropolarimetric studies
of intermediate mass and lower mass T Tauri stars to provide input into
pre-main-sequence stellar evolutionary models.Comment: 8 pages, 8 figures, accepted for publication in Astronomy and
Astrophysic
From the creation of the Women’s Section of Falange (1934) to the electoral campaign in 1936: modalities of falangist women’s intervention in the public sphere
La creaciĂłn de la SecciĂłn Femenina, aunque significa de facto que los falangistas aceptan cierta presencia de “sus” mujeres en la esfera pĂşblica, remite a la defensa de un modelo femenino anclado en el espacio privado. Sus actividades, concebidas como una extensiĂłn del papel domĂ©stico de la mujer al ámbito pĂşblico, son pues esencialmente sociales. En 1936, con la campaña electoral, parecen ampliarse a lo polĂtico.Este trabajo se interroga sobre el sentido y la realidad de esta aparente evoluciĂłn asĂ como sobre las contradicciones de la SecciĂłn Femenina, su dificultad en posicionarse entre la esfera pĂşblica y la privada. Estas contradicciones se hacen patentes en la figura de Rosario Pereda, jefe de la SecciĂłn Femenina de Valladolid y oradora reconocida y apreciada por sus camaradas masculinos.The founding of the Women’s Section of the Falange, despite signifying that the Falangists accept a certain presence of “their” women in the public sphere, defends a feminine model anchored in the private area. Its activities are essentially social, conceived as an extension of the domestic role of women into the public sphere. In 1936, however, with the electoral campaign, these roles seem to be extended to the political domain.The present study aims to analyse the meaning and the reality of this apparent evolution of the Women’s Section with its contradictions and its difficulty in positioning itself between the public and the private spheres. These contradictions become clear in the figure of Rosario Pereda, chief of the Women’s Section of Valladolid, who was a recognized orator esteemed by her masculine comrades
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