26 research outputs found
Characterizing absolutely irreducible integer-valued polynomials over discrete valuation domains
Rings of integer-valued polynomials are known to be atomic, non-factorial
rings furnishing examples for both irreducible elements for which all powers
factor uniquely (\emph{absolutely irreducibles}) and irreducible elements where
some power has a factorization different from the trivial one.
In this paper, we study irreducible polynomials
where is a discrete valuation domain with finite residue field and show
that it is possible to explicitly determine a number that
reduces the absolute irreducibility of to the unique factorization of
. To this end, we establish a connection between the factors of powers of
and the kernel of a certain linear map that we associate to . This
connection yields a characterization of absolute irreducibility in terms of
this so-called \emph{fixed divisor
kernel}. Given a non-trivial element of this kernel, we
explicitly construct non-trivial factorizations of , provided that , where depends on as well as the choice of . We
further show that this bound cannot be improved in general. Additionally, we
provide other (larger) lower bounds for , one of which only depends on the
valuation of the denominator of and the size of the residue class field of
METHODS FOR DISINFECTING TOOLS IN MANAGEMENT OF BANANA XANTHOMONAS WILT DISEASE
ABSTRACT Xanthomonas wilt is the greatest threat to banana production in E. Africa. The disease spreads through insect vectors, contaminated tools and planting materials. Spread by tools can be managed by disinfecting working tools using chemicals or heat. Major challenges in chemical disinfection include lack of knowledge on appropriate concentration of disinfectants and application methods. The most widely used disinfectant is Jik®, containing NaOCl, at recommended rate of 1:5 (Jik/water, v/v). Experiments were carried out to study application methods, comparing dipping tools in varying Jik® concentrations (0.6, 0.9, 1.2%) for varying periods of time (15s-3 min), and wiping tools lightly or vigorously with cloth soaked in disinfectant. Knives were smeared with Xanthomonas cells on 5cm portion on both sides of the blade. Smeared knives were immediately fully immersed in Jik® solutions for the set period of time. Alternatively, smeared blades were wiped with soaked cloth, either lightly (passing cloth ≤2 times over the blade) or vigorously (passing cloth ≥5 times over the blade). After dipping or wiping, blades were used to make incisions into YPGA medium and into stems of the susceptible 2 banana cultivar Kayinja. Colony growth was observed on YPGA over three days while plants were observed for symptom development over 30 days. When applied by dipping 0.6% Jik® required 3min to be effective while 0.9 and 1.2% required at least 1min. Wiping tools lightly was effective at 1.2% while vigorous wiping was effective even with 0.6%. The study concludes it would be effective to use the recommended application rate of 0.6% Jik® only if applied by wiping tools vigorously. To be effective, disinfecting by tools would require at least 0.9% Jik®, which increases costs or and reduces labour productivity due to longer waiting periods
Analysis of Temperature-to-Polarization Leakage in BICEP3 and Keck CMB Data from 2016 to 2018
The Bicep/Keck Array experiment is a series of small-aperture refracting telescopes observing degree-scale Cosmic Microwave Background polarization from the South Pole in search of a primordial B-mode signature. As a pair differencing experiment, an important systematic that must be controlled is the differential beam response between the co-located, orthogonally polarized detectors. We use high-fidelity, in-situ measurements of the beam response to estimate the temperature-to-polarization (T → P) leakage in our latest data including observations from 2016 through 2018. This includes three years of Bicep3 observing at 95 GHz, and multifrequency data from Keck Array. Here we present band-averaged far-field beam maps, differential beam mismatch, and residual beam power (after filtering out the leading difference modes via deprojection) for these receivers. We show preliminary results of "beam map simulations," which use these beam maps to observe a simulated temperature (no Q/U) sky to estimate T → P leakage in our real data
Observing low elevation sky and the CMB Cold Spot with BICEP3 at the South Pole
BICEP3 is a 520 mm aperture on-axis refracting telescope at the South Pole, which observes the polarization of the cosmic microwave background (CMB) at 95 GHz to search for the B-mode signal from inflationary gravitational waves. In addition to this main target, we have developed a low-elevation observation strategy to extend coverage of the Southern sky at the South Pole, where BICEP3 can quickly achieve degree-scale E-mode measurements over a large area. An interesting E-mode measurement is probing a potential polarization anomaly around the CMB Cold Spot. During the austral summer seasons of 2018-19 and 2019-20, BICEP3 observed the sky with a flat mirror to redirect the beams to various low elevation ranges. The preliminary data analysis shows degree-scale E-modes measured with high signal-to-noise ratio
Analysis of Temperature-to-Polarization Leakage in BICEP3 and Keck CMB Data from 2016 to 2018
The Bicep/Keck Array experiment is a series of small-aperture refracting telescopes observing degree-scale Cosmic Microwave Background polarization from the South Pole in search of a primordial B-mode signature. As a pair differencing experiment, an important systematic that must be controlled is the differential beam response between the co-located, orthogonally polarized detectors. We use high-fidelity, in-situ measurements of the beam response to estimate the temperature-to-polarization (T → P) leakage in our latest data including observations from 2016 through 2018. This includes three years of Bicep3 observing at 95 GHz, and multifrequency data from Keck Array. Here we present band-averaged far-field beam maps, differential beam mismatch, and residual beam power (after filtering out the leading difference modes via deprojection) for these receivers. We show preliminary results of "beam map simulations," which use these beam maps to observe a simulated temperature (no Q/U) sky to estimate T → P leakage in our real data
Polarization calibration of the BICEP3 CMB polarimeter at the South Pole
The BICEP3 CMB Polarimeter is a small-aperture refracting telescope located at the South Pole and is specifically designed to search for the possible signature of inflationary gravitational waves in the Cosmic Microwave Background (CMB). The experiment measures polarization on the sky by differencing the signal of co-located, orthogonally polarized antennas coupled to Transition Edge Sensor (TES) detectors. We present precise measurements of the absolute polarization response angles and polarization efficiencies for nearly all of BICEP3's ~800 functioning polarization-sensitive detector pairs from calibration data taken in January 2018. Using a Rotating Polarized Source (RPS), we mapped polarization response for each detector over a full 360 degrees of source rotation and at multiple telescope boresight rotations from which per-pair polarization properties were estimated. In future work, these results will be used to constrain signals predicted by exotic physical models such as Cosmic Birefringence
Observing low elevation sky and the CMB Cold Spot with BICEP3 at the South Pole
BICEP3 is a 520 mm aperture on-axis refracting telescope at the South Pole, which observes the polarization of the cosmic microwave background (CMB) at 95 GHz to search for the B-mode signal from inflationary gravitational waves. In addition to this main target, we have developed a low-elevation observation strategy to extend coverage of the Southern sky at the South Pole, where BICEP3 can quickly achieve degree-scale E-mode measurements over a large area. An interesting E-mode measurement is probing a potential polarization anomaly around the CMB Cold Spot. During the austral summer seasons of 2018-19 and 2019-20, BICEP3 observed the sky with a flat mirror to redirect the beams to various low elevation ranges. The preliminary data analysis shows degree-scale E-modes measured with high signal-to-noise ratio
Finishing the euchromatic sequence of the human genome
The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead