46,539 research outputs found
Strong Lensing Analysis of the Powerful Lensing Cluster MACS J2135.2-0102 (=0.33)
We present a light-traces-mass (LTM) strong-lensing model of the massive
lensing cluster MACS J2135.2-0102 (=0.33; hereafter MACS2135), known in part
for hosting the Cosmic Eye galaxy lens. MACS2135 is also known to multiply-lens
a 2.3 sub-mm galaxy near the Brightest Cluster Galaxy (BCG), as well as a
prominent, triply-imaged system at a large radius of 37" south of the
BCG. We use the latest available Hubble imaging to construct an accurate
lensing model for this cluster, identifying six new multiply-imaged systems
with the guidance of our LTM method, so that we have roughly quadrupled the
number of lensing constraints. We determine that MACS2135 is amongst the top
lensing clusters known, comparable in size to the Hubble Frontier Fields. For a
source at , we find an effective Einstein radius of
", enclosing . We
make our lens model, including mass and magnification maps, publicly available,
in anticipation of searches for high- galaxies with the James Webb Space
Telescope for which this cluster is a compelling target.Comment: 7 pages, 2 figures (3 subfigures in total), 1 table; Published in
ApJ; V2: accepted versio
Anisotropies in Non-Thermal Distortions of Cosmic Light from Photon-Axion Conversion
Ultralight axions which couple sufficiently strongly to photons can leave
imprints on the sky at diverse frequencies by mixing with cosmic light in the
presence of background magnetic fields. We explore such direction dependent
grey-body distortions of the CMB spectrum, enhanced by resonant conditions in
the IGM plasma. We also find that if such axions are produced in the early
universe and represent a subdominant dark radiation component today, they could
convert into X-rays in supervoids, and brighten them at X-ray frequencies.Comment: 11 pages, 1 figur
An integrated molecular and conventional breeding scheme for enhancing genetic gain in maize in Africa
Open Access Journal; Published online: 06 Nov 2019Maize production in West and Central Africa (WCA) is constrained by a wide range of interacting stresses that keep productivity below potential yields. Among the many problems afflicting maize production in WCA, drought, foliar diseases, and parasitic weeds are the most critical. Several decades of efforts devoted to the genetic improvement of maize have resulted in remarkable genetic gain, leading to increased yields of maize on farmers’ fields. The revolution unfolding in the areas of genomics, bioinformatics, and phenomics is generating innovative tools, resources, and technologies for transforming crop breeding programs. It is envisaged that such tools will be integrated within maize breeding programs, thereby advancing these programs and addressing current and future challenges. Accordingly, the maize improvement program within International Institute of Tropical Agriculture (IITA) is undergoing a process of modernization through the introduction of innovative tools and new schemes that are expected to enhance genetic gains and impact on smallholder farmers in the region. Genomic tools enable genetic dissections of complex traits and promote an understanding of the physiological basis of key agronomic and nutritional quality traits. Marker-aided selection and genome-wide selection schemes are being implemented to accelerate genetic gain relating to yield, resilience, and nutritional quality. Therefore, strategies that effectively combine genotypic information with data from field phenotyping and laboratory-based analysis are currently being optimized. Molecular breeding, guided by methodically defined product profiles tailored to different agroecological zones and conditions of climate change, supported by state-of-the-art decision-making tools, is pivotal for the advancement of modern, genomics-aided maize improvement programs. Accelerated genetic gain, in turn, catalyzes a faster variety replacement rate. It is critical to forge and strengthen partnerships for enhancing the impacts of breeding products on farmers’ livelihood. IITA has well-established channels for delivering its research products/technologies to partner organizations for further testing, multiplication, and dissemination across various countries within the subregion. Capacity building of national agricultural research system (NARS) will facilitate the smooth transfer of technologies and best practices from IITA and its partners
Are anonymity-seekers just like everybody else? An analysis of contributions to Wikipedia from Tor
User-generated content sites routinely block contributions from users of
privacy-enhancing proxies like Tor because of a perception that proxies are a
source of vandalism, spam, and abuse. Although these blocks might be effective,
collateral damage in the form of unrealized valuable contributions from
anonymity seekers is invisible. One of the largest and most important
user-generated content sites, Wikipedia, has attempted to block contributions
from Tor users since as early as 2005. We demonstrate that these blocks have
been imperfect and that thousands of attempts to edit on Wikipedia through Tor
have been successful. We draw upon several data sources and analytical
techniques to measure and describe the history of Tor editing on Wikipedia over
time and to compare contributions from Tor users to those from other groups of
Wikipedia users. Our analysis suggests that although Tor users who slip through
Wikipedia's ban contribute content that is more likely to be reverted and to
revert others, their contributions are otherwise similar in quality to those
from other unregistered participants and to the initial contributions of
registered users.Comment: To appear in the IEEE Symposium on Security & Privacy, May 202
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