3,474 research outputs found
In ovo time-lapse analysis after dorsal neural tube ablation shows rerouting of chick hindbrain neural crest
Previous analyses of single neural crest cell trajectories
have suggested important roles for interactions between
neural crest cells and the environment, and amongst neural
crest cells. To test the relative contribution of intrinsic
versus extrinsic information in guiding cells to their
appropriate sites, we ablated subpopulations of
premigratory chick hindbrain neural crest and followed
the remaining neural crest cells over time using a new in
ovo imaging technique. Neural crest cell migratory
behaviors are dramatically different in ablated compared
with unoperated embryos. Deviations from normal
migration appear either shortly after cells emerge from the
neural tube or en route to the branchial arches, areas where
cell-cell interactions typically occur between neural crest
cells in normal embryos. Unlike the persistent, directed
trajectories in normal embryos, neural crest cells
frequently change direction and move somewhat
chaotically after ablation. In addition, the migration of
neural crest cells in collective chains, commonly observed
in normal embryos, was severely disrupted. Hindbrain
neural crest cells have the capacity to reroute their
migratory pathways and thus compensate for missing
neural crest cells after ablation of neighboring populations.
Because the alterations in neural crest cell migration are
most dramatic in regions that would normally foster cell-cell
interactions, the trajectories reported here argue that
cell-cell interactions have a key role in the shaping of the
neural crest migration
A comparison of the use of vacuum metal deposition versus cyanoacrylate fuming for visualisation of fingermarks and grab impressions on fabrics
Both vacuum metal deposition (VMD) and cyanoacrylate fuming (CAF) are techniques used to visualise latent fingermarks on smooth non-porous surfaces such as plastic and glass. VMD was initially investigated in the 1970s as to its effectiveness for visualising prints on fabrics, but was abandoned when radioactive sulphur dioxide was found to be more effective. However, interest in VMD was resurrected in the 1990s when CAF was also used routinely. We now report on studies to determine whether VMD or CAF is the more effective technique for the detection of marks on fabrics. Four different fabrics, nylon, polyester, polycotton and cotton, were utilised during this study, along with 15 donors who ranged in their age and ability to leave fingermarks, from good to medium to poor, thus reflecting the general population. Once samples were collected they were kept for a determined time (1, 2, 3, 4, 5, 6, 7, 14, 21 or 28 days) and then treated using either the gold and zinc metal VMD process or standard cyanoacrylate fuming.The smoother fabrics, such as nylon, consistently produced greater ridge detail whereas duller fabrics, like cotton tended only to show empty prints and impressions of where the fabric had been touched, rather than any ridge details. The majority of fabrics did however allow the development of touch marks that could be targeted for DNA taping which potentially could lead to a DNA profile. Of the two techniques VMD was around 5 times more effective than CAF, producing a greater amount of ridge detail, palmar flexion creases and target areas on more samples and fabrics
Robotic Astronomy with the Faulkes Telescopes and Las Cumbres Observatory Global Telescope
We present results from ongoing science projects conducted by members of the
Faulkes Telescope (FT) team and Las Cumbres Observatory Global Telescope
(LCOGT). Many of these projects incorporate observations carried out and
analysed by FT users, comprising amateur astronomers and schools.
We also discuss plans for the further development of the LCOGT network.Comment: 8 pages, 2 figures, conference proceedings from "Workshop on Robotic
Autonomous Observatories", held at Malaga, Spain from 18-21 May 2009,
acccepted for publication in Advances in Astronom
Continued monitoring of LMXBs with the Faulkes Telescopes
The Faulkes Telescope Project is an educational and research arm of the Las Cumbres Observatory Global Telescope Network (LCOGTN). It has two 2-metre robotic telescopes, located at Haleakala on Maui (FT North) and Siding Spring in Australia (FT South). It is planned for these telescopes to be complemented by a research network of eighteen 1-metre telescopes, along with an educational network of twenty-eight 0.4-metre telescopes, providing 24 hour coverage of both northern and southern hemispheres.
We have been conducting a monitoring project of 13 low-mass X-ray binaries (LMXBs) using FT North since early 2006. The introduction of FT South has allowed us to extend this to monitor a total of 30 LMXBs (see target list, Section 4). New instrumentation will allow us to expand this project to include both infrared wavelengths (z and y band) and spectroscopy. Brighter targets (~ 16 - 18 mag.) are imaged weekly in V, R and iā bands (SNR ~ 50), while fainter ones (> 18 mag.) are observed only in iā band (SNR ~ 20). We alter this cadence in response to our own analysis or Astronomers Telegrams (ATels)
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