2,686 research outputs found
THE TAXONOMIC STATUS OF THE WYOMING TOAD, BUFO BAXTERI PORTER
The population of toads in southeastern Wyoming named Bufo hemiophrys baxteri by Porter in 1968 is presumed to be extinct in nature, except perhaps for released, captive-bred specimens. It is sufficiently distinct in several respects, and sufficiently isolated geographically from its nearest rela- tive, B. h. hemiophrys, that it should be regarded as a distinct species, forming a superspecies group with B. hemiophrys
Resolving genetic engineering signatures in yeast on-site with the MinION and iSeq
Generating an assembly that captures all of the genome and plasmid modifications resulting from metabolic engineering is essential for quality control, connecting genotype to phenotype, establishing and protecting intellectual property, and generating âground truthâ for monitoring potential release events. Furthermore, high quality de novo assemblies can be used to accurately determine the presence and function of metabolic engineering signatures in an unknown sample. Here, we use two new inexpensive sequencers, the Oxford Nanopore MinION and the Illumina iSeq, to enable fast acquisition of sequence on-site. We also use new processing algorithms to enable fast transformation of sequence information into a high-quality genome assembly. The resulting pipeline can generate de novo microbial genome assemblies that capture complete chromosomal pathways and episomal plasmids. We further extend the pipeline to resequence six nonconventional yeasts of interest for metabolic engineering. To establish the most accurate workflow, we evaluated four nanopore de novo assemblers and three polishing algorithms at varying genome coverage depths for the lab strain S. cerevisiae CEN.PK113-7D. Our results show that (1) nanopore genome coverage depth must be at least 40X, (2) Flye and Canu are currently the best assemblers due to their combination of structure, completeness, and accuracy, and (3) Illumina data is essential for polishing. Our final pipeline (Figure 1A) generated a better S. cerevisiae CEN.PK113-7D assembly than the publicly available reference genome.
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Review: \u3ci\u3eVeratrum californicum\u3c/i\u3e Alkaloids
Veratrum spp. grow throughout the world and are especially prevalent in high mountain meadows of North America. All parts of Veratrum plants have been used for the treatment of ailments including injuries, hypertension, and rheumatic pain since as far back as the 1600s. Of the 17â45 Veratrum spp., Veratrum californicum alkaloids have been proven to possess favorable medicinal properties associated with inhibition of hedgehog (Hh) pathway signaling. Aberrant Hh signaling leads to proliferation of over 20 cancers, including basal cell carcinoma, prostate and colon among others. Six of the most well-studied V. californicum alkaloids are cyclopamine (1), veratramine (2), isorubijervine (3), muldamine (4), cycloposine (5), and veratrosine (6). Recent inspection of the ethanolic extract from V. californicum root and rhizome via liquid chromatographyâmass spectrometry has detected up to five additional alkaloids that are proposed to be verazine (7), etioline (8), tetrahydrojervine (9), dihydrojervine (10), 22-keto-26-aminocholesterol (11). For each alkaloid identified or proposed in V. californicum, this review surveys literature precedents for extraction methods, isolation, identification, characterization and bioactivity to guide natural product drug discovery associated with this medicinal plant
A comparative study of WASP-67b and HAT-P-38b from WFC3 data
Atmospheric temperature and planetary gravity are thought to be the main
parameters affecting cloud formation in giant exoplanet atmospheres. Recent
attempts to understand cloud formation have explored wide regions of the
equilibrium temperature-gravity parameter space. In this study, we instead
compare the case of two giant planets with nearly identical equilibrium
temperature ( ) and gravity (. During Cycle 23, we collected WFC3/G141
observations of the two planets, WASP-67 b and HAT-P-38 b. HAT-P-38 b, with
mass 0.42 M and radius 1.4 , exhibits a relatively
clear atmosphere with a clear detection of water. We refine the orbital period
of this planet with new observations, obtaining . WASP-67 b, with mass 0.27 M and radius 0.83
, shows a more muted water absorption feature than that of
HAT-P-38 b, indicating either a higher cloud deck in the atmosphere or a more
metal-rich composition. The difference in the spectra supports the hypothesis
that giant exoplanet atmospheres carry traces of their formation history.
Future observations in the visible and mid-infrared are needed to probe the
aerosol properties and constrain the evolutionary scenario of these planets.Comment: 16 pages, 17 figures, 8 tables, accepted for publication in The
Astronomical Journa
Exclusive Production of Higgs Bosons in Hadron Colliders
We study the exclusive, double--diffractive production of the Standard Model
Higgs particle in hadronic collisions at LHC and FNAL (upgraded) energies. Such
a mechanism would provide an exceptionally clean signal for experimental
detection in which the usual penalty for triggering on the rare decays of the
Higgs could be avoided. In addition, because of the color singlet nature of the
hard interaction, factorization is expected to be preserved, allowing the
cross--section to be related to similar hard--diffractive events at HERA.
Starting from a Fock state expansion in perturbative QCD, we obtain an estimate
for the cross section in terms of the gluon structure functions squared of the
colliding hadrons. Unfortunately, our estimates yield a production rate well
below what is likely to be experimentally feasible.Comment: 17 pages, RevTeX file, four uufiled PostScript figures. UMPP #94-177.
(Revised version. Some mistakenly missing Feynman diagrams are now added.
Results do not change qualitatively. Paper reorganized.
Combinatorics of renormalization as matrix calculus
We give a simple presentation of the combinatorics of renormalization in
perturbative quantum field theory in terms of triangular matrices. The
prescription, that may be of calculational value, is derived from first
principles, to wit, the ``Birkhoff decomposition'' in the Hopf-algebraic
description of renormalization by Connes and Kreimer.Comment: 10 pages, revised version, typos corrected, to appear in Phys. Lett.
Instrumentation for Routine Analysis of Acrylamide in French Fries: Assessing Limitations for Adoption
The purpose of this experimental review was to detect acrylamide in French fries using methods most adaptable to the food process industry for quality control assessment of products. French fries were prepared at different cook times using the same fryer oil over a five-day period to assess the influence of oil degradation and monitor trends in acrylamide formation. Acrylamide detection was performed using LC-MS, GC-MS and FT-NIR. The low levels of acrylamide produced during frying, low molecular weight of the analyte, and complexity of the potato matrix make routine acrylamide measurement challenging in a well-outfitted analytical lab with trained personnel. The findings of this study are presented from the perspective of pros and cons of each acrylamide measurement method in enough detail for food processors to appraise the method that may work best for them based on their available instrumentation and extent of personnel training
Two real parton contributions to non-singlet kernels for exclusive QCD DGLAP evolution
Results for the two real parton differential distributions needed for
implementing a next-to-leading order (NLO) parton shower Monte Carlo are
presented. They are also integrated over the phase space in order to provide
solid numerical control of the MC codes and for the discussion of the
differences between the standard factorization and Monte Carlo
implementation at the level of inclusive NLO evolution kernels. Presented
results cover the class of non-singlet diagrams entering into NLO kernels. The
classic work of Curci-Furmanski-Pertonzio was used as a guide in the
calculations.Comment: 34 pages, 3 figure
How Anisotropic is our Universe?
Large-scale cosmic microwave background anisotropies in homogeneous, globally
anisotropic cosmologies are investigated. We perform a statistical analysis in
which the four-year data from the Cosmic Background Explorer satellite is
searched for the specific anisotropy patterns predicted by these models and
thereby set definitive upper limits on the amount of shear, and
vorticity, , which are orders of magnitude stronger than previous
constraints. We comment on how these results might impact our understanding of
primordial global anisotropy.Comment: 12 pages (1 figure), uses RevTex and psfig, submitted to PR
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