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Abundance of conserved CRISPR-Cas9 target sites within the highly polymorphic genomes of Anopheles and Aedes mosquitoes.
A number of recent papers report that standing genetic variation in natural populations includes ubiquitous polymorphisms within target sites for Cas9-based gene drive (CGD) and that these "drive resistant alleles" (DRA) preclude the successful application of CGD for managing these populations. Here we report the results of a survey of 1280 genomes of the mosquitoes Anopheles gambiae, An. coluzzii, and Aedes aegypti in which we determine that ~90% of all protein-encoding CGD target genes in natural populations include at least one target site with no DRAs at a frequency of ≥1.0%. We conclude that the abundance of conserved target sites in mosquito genomes and the inherent flexibility in CGD design obviates the concern that DRAs present in the standing genetic variation of mosquito populations will be detrimental to the deployment of this technology for population modification strategies
Gaussian processes for choosing laser parameters for driven, dissipative Rydberg aggregates
To facilitate quantum simulation of open quantum systems at finite
temperatures, an important ingredient is to achieve thermalization on a given
time-scale. We consider a Rydberg aggregate (an arrangement of Rydberg atoms
that interact via long-range interactions) embedded in a laser-driven atomic
environment. For the smallest aggregate (two atoms), suitable laser parameters
can be found by brute force scanning of the four tunable laser parameters. For
more atoms, however, such parameter scans are too computationally costly. Here
we apply Gaussian processes to predict the thermalization performance as a
function of the laser parameters for two-atom and four-atom aggregates. These
predictions perform remarkably well using just 1000 simulations, demonstrating
the utility of Gaussian processes in an atomic physics setting. Using this
approach, we find and present effective laser parameters for generating
thermalization, the robustness of these parameters to variation, as well as
different thermalization dynamics
Cosmic homogeneity demonstrated with luminous red galaxies
We test the homogeneity of the Universe at with the Luminous Red
Galaxy (LRG) spectroscopic sample of the Sloan Digital Sky Survey. First, the
mean number of LRGs within completely surveyed LRG-centered spheres of
comoving radius is shown to be proportional to at radii greater than
. The test has the virtue that it does not rely
on the assumption that the LRG sample has a finite mean density; its results
show, however, that there \emph{is} such a mean density. Secondly, the survey
sky area is divided into 10 disjoint solid angular regions and the fractional
rms density variations of the LRG sample in the redshift range
among these () regions is found to be 7
percent of the mean density. This variance is consistent with typical biased
\lcdm models and puts very strong constraints on the quality of SDSS
photometric calibration.Comment: submitted to Ap
First results from the CRESST-III low-mass dark matter program
The CRESST experiment is a direct dark matter search which aims to measure
interactions of potential dark matter particles in an earth-bound detector.
With the current stage, CRESST-III, we focus on a low energy threshold for
increased sensitivity towards light dark matter particles. In this manuscript
we describe the analysis of one detector operated in the first run of
CRESST-III (05/2016-02/2018) achieving a nuclear recoil threshold of 30.1eV.
This result was obtained with a 23.6g CaWO crystal operated as a cryogenic
scintillating calorimeter in the CRESST setup at the Laboratori Nazionali del
Gran Sasso (LNGS). Both the primary phonon/heat signal and the simultaneously
emitted scintillation light, which is absorbed in a separate
silicon-on-sapphire light absorber, are measured with highly sensitive
transition edge sensors operated at ~15mK. The unique combination of these
sensors with the light element oxygen present in our target yields sensitivity
to dark matter particle masses as low as 160MeV/c.Comment: 9 pages, 9 figure
An age-of-allele test of neutrality for transposable element insertions
How natural selection acts to limit the proliferation of transposable
elements (TEs) in genomes has been of interest to evolutionary biologists for
many years. To describe TE dynamics in populations, many previous studies have
used models of transposition-selection equilibrium that rely on the assumption
of a constant rate of transposition. However, since TE invasions are known to
happen in bursts through time, this assumption may not be reasonable in natural
populations. Here we propose a test of neutrality for TE insertions that does
not rely on the assumption of a constant transposition rate. We consider the
case of TE insertions that have been ascertained from a single haploid
reference genome sequence and have subsequently had their allele frequency
estimated in a population sample. By conditioning on the age of an individual
TE insertion (using information contained in the number of substitutions that
have occurred within the TE sequence since insertion), we determine the
probability distribution for the insertion allele frequency in a population
sample under neutrality. Taking models of varying population size into account,
we then evaluate predictions of our model against allele frequency data from
190 retrotransposon insertions sampled from North American and African
populations of Drosophila melanogaster. Using this non-equilibrium model, we
are able to explain about 80% of the variance in TE insertion allele
frequencies based on age alone. Controlling both for nonequilibrium dynamics of
transposition and host demography, we provide evidence for negative selection
acting against most TEs as well as for positive selection acting on a small
subset of TEs. Our work establishes a new framework for the analysis of the
evolutionary forces governing large insertion mutations like TEs, gene
duplications or other copy number variants.Comment: 40 pages, 6 figures, Supplemental Data available: [email protected]
Bulk NaI(Tl) scintillation low energy events selection with the ANAIS-0 module
Dark matter particles scattering off some target nuclei are expected to
deposit very small energies in form of nuclear recoils (below 100 keV). Because
of the low scintillation efficiency for nuclear recoils vs. electron recoils,
in most of the scintillating targets considered in the search for dark matter,
the region below 10 keVee concentrates most of the expected dark matter signal.
For this reason, very low energy threshold (at or below 2 keVee) and very low
background are required. This is the case of the ANAIS (Annual modulation with
NaI Scintillators) experiment. A good knowledge of the detector response
function for real scintillation events, a good characterization of other
anomalous or noise event populations contributing in that energy range, and the
development of convenient filtering procedures for the latter are mandatory to
achieve the required low background at such a low energy. In this work we will
present the specific protocols developed to select bulk scintillation events in
NaI(Tl), and its application to data obtained with the ANAIS-0 prototype.
Slight differences in time constants are expected in scintillation pulses
produced by nuclear or electron recoils in NaI(Tl), so in order to analyze the
effect of these filtering procedures in the case of a recoil population
attributable to dark matter, data from a neutron calibration have been used.Comment: 13 pages, 22 figure
The Chandra Galactic Bulge Survey: optical catalogue and point-source counterparts to X-ray sources
As part of the Chandra Galactic Bulge Survey (GBS), we present a catalogue of
optical sources in the GBS footprint. This consists of two regions centered at
Galactic latitude b = 1.5 degrees above and below the Galactic Centre, spanning
(l x b) = (6x1) degrees. The catalogue consists of 2 or more epochs of
observations for each line of sight in r', i' and H{\alpha} filters. It is
complete down to r' = 20.2 and i' = 19.2 mag; the mean 5{\sigma} depth is r' =
22.5 and i' = 21.1 mag. The mean root-mean-square residuals of the astrometric
solutions is 0.04 arcsec. We cross-correlate this optical catalogue with the
1640 unique X-ray sources detected in Chandra observations of the GBS area, and
find candidate optical counterparts to 1480 X-ray sources. We use a false alarm
probability analysis to estimate the contamination by interlopers, and expect ~
10 per cent of optical counterparts to be chance alignments. To determine the
most likely counterpart for each X-ray source, we compute the likelihood ratio
for all optical sources within the 4{\sigma} X-ray error circle. This analysis
yields 1480 potential counterparts (~ 90 per cent of the sample). 584
counterparts have saturated photometry (r'<17, i'<16), indicating these objects
are likely foreground sources and the real counterparts. 171 candidate
counterparts are detected only in the i'-band. These sources are good qLMXB and
CV candidates as they are X-ray bright and likely located in the Bulge.Comment: 18 pages, 18 figures. Published in MNRAS. 2016MNRAS.458.4530
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