15 research outputs found
Candidate tidal dwarf galaxies associated with the Stephan's Quintet
We present kinematic and photometric evidence for the presence of seven
candidate tidal dwarf galaxies in Stephan's quintet. The central regions of the
two most probable parent galaxies, N7319 and N7318B, contain little or no gas
whereas the intragroup medium, and particularly the optical tails that seem to
be associated with N7318B are rich in cold and ionized gas.
Two tidal-dwarf candidates may be located at the edge of a tidal tail, one
within a tail and for four others there is no obvious stellar/gaseous bridge
between them and the parent galaxy. Two of the candidates are associated with
HI clouds, one of which is, in addition, associated with a CO cloud. All seven
regions have low continuum fluxes and high H luminosity densities
(F(H) = 1 -- 60 10 erg s cm). Their
magnitudes (M --16.1 to --12.6), sizes ( 3.5 h kpc),
colors (typically ) and gas velocity gradients ( 8 -- 26
h km s kpc) are typical for tidal dwarf galaxies. In
addition the ratios between their star formation rates determined from
H and from the B band luminosity are typical of other tidal dwarf
galaxies. The masses of the tidal dwarf galaxies in Stephan's quintet range
from 2 10 to 10 M and the median value for
their inferred mass-to-light ratios is 7 M/L.Comment: Accepted for publication in Astronomical Journal (23p 11figures
High radiofrequency radiation at Stockholm Old Town: An exposimeter study including the Royal Castle, Supreme Court, three major squares and the Swedish Parliament
A NudE/14-3-3 Pathway Coordinates Dynein and the Kinesin Khc73 to Position the Mitotic Spindle
The Challenges of the Integration of Cancer Survivorship Care Plans with Electronic Medical Records
Quantifying receptor trafficking and colocalization with confocal microscopy
Confocal microscopy is a powerful tool for the study of cellular receptor trafficking and endocytosis. Unbiased and robust image analysis workflows are required for the identification, and study, of aberrant trafficking. After a brief review of related strategies, identifying both good and bad practice, custom workflows for the analysis of live cell 3D time-lapse data are presented. Strategies for data pre-processing, including denoising and background subtraction are considered. We use a 3D level set protocol to accurately segment cells using only the signal from fluorescently labelled receptor. A protocol for the quantification of changes to subcellular receptor distribution over time is then presented. As an example, ligand stimulated trafficking of epidermal growth factor receptor (EGFR) is shown to be significantly reduced in both AG1478 and Dynasore treated cells. Protocols for the quantitative analysis of colocalization between receptor and endosomes are also introduced, including strategies for signal isolation and statistical testing. By calculating the Manders and Pearson coefficients, both co-occurrence and correlation can be assessed. A statistically significant decrease in the level of ligand induced co-occurrence between EGFR and rab5 positive endosomes is demonstrated for both the AG1478 and Dynasore treated cells relative to a control. Finally, a strategy for the visualisation of co-occurrence is presented, which provides an unbiased alternative to colour overlays.</p