1,873 research outputs found
Transcription activator like effector (TALE)-directed piggyBac transposition in human cells.
Insertional therapies have shown great potential for combating genetic disease and safer methods would undoubtedly broaden the variety of possible illness that can be treated. A major challenge that remains is reducing the risk of insertional mutagenesis due to random insertion by both viral and non-viral vectors. Targetable nucleases are capable of inducing double-stranded breaks to enhance homologous recombination for the introduction of transgenes at specific sequences. However, off-target DNA cleavages at unknown sites can lead to mutations that are difficult to detect. Alternatively, the piggyBac transposase is able perform all of the steps required for integration; therefore, cells confirmed to contain a single copy of a targeted transposon, for which its location is known, are likely to be devoid of aberrant genomic modifications. We aimed to retarget transposon insertions by comparing a series of novel hyperactive piggyBac constructs tethered to a custom transcription activator like effector DNA-binding domain designed to bind the first intron of the human CCR5 gene. Multiple targeting strategies were evaluated using combinations of both plasmid-DNA and transposase-protein relocalization to the target sequence. We demonstrated user-defined directed transposition to the CCR5 genomic safe harbor and isolated single-copy clones harboring targeted integrations
Vacuum Cherenkov Radiation In Quantum Electrodynamics With High-Energy Lorentz Violation
We study phenomena predicted by a renormalizable, CPT invariant extension of
the Standard Model that contains higher-dimensional operators and violates
Lorentz symmetry explicitly at energies greater than some scale Lambda_{L}. In
particular, we consider the Cherenkov radiation in vacuo. In a rather general
class of dispersion relations, there exists an energy threshold above which
radiation is emitted. The threshold is enhanced in composite particles by a
sort of kinematic screening mechanism. We study the energy loss and compare the
predictions of our model with known experimental bounds on Lorentz violating
parameters and observations of ultrahigh-energy cosmic rays. We argue that the
scale of Lorentz violation Lambda_{L} (with preserved CPT invariance) can be
smaller than the Planck scale, actually as small as 10^{14}-10^{15} GeV. Our
model also predicts the Cherenkov radiation of neutral particles.Comment: 27 pages, 2 figures; v2: typos corrected, more references, some more
comments - PR
Detection of an atmosphere around the super-Earth 55 Cancri e
We report the analysis of two new spectroscopic observations of the
super-Earth 55 Cancri e, in the near infrared, obtained with the WFC3 camera
onboard the HST. 55 Cancri e orbits so close to its parent star, that
temperatures much higher than 2000 K are expected on its surface. Given the
brightness of 55 Cancri, the observations were obtained in scanning mode,
adopting a very long scanning length and a very high scanning speed. We use our
specialized pipeline to take into account systematics introduced by these
observational parameters when coupled with the geometrical distortions of the
instrument. We measure the transit depth per wavelength channel with an average
relative uncertainty of 22 ppm per visit and find modulations that depart from
a straight line model with a 6 confidence level. These results suggest
that 55 Cancri e is surrounded by an atmosphere, which is probably
hydrogen-rich. Our fully Bayesian spectral retrieval code, T-REx, has
identified HCN to be the most likely molecular candidate able to explain the
features at 1.42 and 1.54 m. While additional spectroscopic observations
in a broader wavelength range in the infrared will be needed to confirm the HCN
detection, we discuss here the implications of such result. Our chemical model,
developed with combustion specialists, indicates that relatively high mixing
ratios of HCN may be caused by a high C/O ratio. This result suggests this
super-Earth is a carbon-rich environment even more exotic than previously
thought.Comment: 10 pages, 10 figures, 4 tables, Accepted for publication in Ap
A population study of gaseous exoplanets
We present here the analysis of 30 gaseous extrasolar planets, with
temperatures between 600 and 2400 K and radii between 0.35 and 1.9
. The quality of the HST/WFC3 spatially scanned data combined
with our specialized analysis tools allow us to study the largest and most
self-consistent sample of exoplanetary transmission spectra to date and examine
the collective behavior of warm and hot gaseous planets rather than isolated
case-studies. We define a new metric, the Atmospheric Detectability Index (ADI)
to evaluate the statistical significance of an atmospheric detection and find
statistically significant atmospheres around 16 planets out of the 30 analysed.
For most of the Jupiters in our sample, we find the detectability of their
atmospheres to be dependent on the planetary radius but not on the planetary
mass. This indicates that planetary gravity plays a secondary role in the state
of gaseous planetary atmospheres. We detect the presence of water vapour in all
of the statistically detectable atmospheres, and we cannot rule out its
presence in the atmospheres of the others. In addition, TiO and/or VO
signatures are detected with 4 confidence in WASP-76 b, and they are
most likely present in WASP-121 b. We find no correlation between expected
signal-to-noise and atmospheric detectability for most targets. This has
important implications for future large-scale surveys.Comment: 14 pages, 12 figures, 3 tables, published in A
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