1,525 research outputs found
Computations of height higher Real -theory spectra at prime
We completely compute the -homotopy fixed point spectral sequences at
prime for the height Lubin-Tate theory , in the case of finite
subgroups of the Morava stabilizer group for and
. Our computation uses recently developed equivariant techniques since
Hill-Hopkins-Ravenel. We also compute the -graded - and
-homotopy fixed point spectral sequences where is a
non-trivial one dimensional -representation.Comment: 48 pages, comments welcome
F-theory and linear sigma models
We present an explicit method for translating between the linear sigma model
and the spectral cover description of SU(r) stable bundles over an elliptically
fibered Calabi-Yau manifold. We use this to investigate the 4-dimensional
duality between (0,2) heterotic and F-theory compactifications. We indirectly
find that much interesting heterotic information must be contained in the
`spectral bundle' and in its dual description as a gauge theory on multiple
F-theory 7-branes.
A by-product of these efforts is a method for analyzing semistability and the
splitting type of vector bundles over an elliptic curve given as the sheaf
cohomology of a monad.Comment: 40 pages, no figures; minor cosmetic reorganization of section 4;
reference [6] update
Breaking the curse of dimensionality in regression
Models with many signals, high-dimensional models, often impose structures on
the signal strengths. The common assumption is that only a few signals are
strong and most of the signals are zero or close (collectively) to zero.
However, such a requirement might not be valid in many real-life applications.
In this article, we are interested in conducting large-scale inference in
models that might have signals of mixed strengths. The key challenge is that
the signals that are not under testing might be collectively non-negligible
(although individually small) and cannot be accurately learned. This article
develops a new class of tests that arise from a moment matching formulation. A
virtue of these moment-matching statistics is their ability to borrow strength
across features, adapt to the sparsity size and exert adjustment for testing
growing number of hypothesis. GRoup-level Inference of Parameter, GRIP, test
harvests effective sparsity structures with hypothesis formulation for an
efficient multiple testing procedure. Simulated data showcase that GRIPs error
control is far better than the alternative methods. We develop a minimax
theory, demonstrating optimality of GRIP for a broad range of models, including
those where the model is a mixture of a sparse and high-dimensional dense
signals.Comment: 51 page
Occurrence of L-iduronic acid and putative D-glucuronyl C5-epimerases in prokaryotes
Glycosaminoglycans (GAGs) are polysaccharides that are typically present in a wide diversity of animal tissue. Most common GAGs are well-characterized and pharmaceutical applications exist for many of these compounds, e.g. heparin and hyaluronan. In addition, also bacterial glycosaminoglycan-like structures exist. Some of these bacterial GAGs have been characterized, but until now no bacterial GAG has been found that possesses the modifications that are characteristic for many of the animal GAGs such as sulfation and C5-epimerization. Nevertheless, the latter conversion may also occur in bacterial and archaeal GAGs, as some prokaryotic polysaccharides have been demonstrated to contain L-iduronic acid. However, experimental evidence for the enzymatic synthesis of L-iduronic acid in prokaryotes is as yet lacking. We therefore performed an in silico screen for D-glucuronyl C5-epimerases in prokaryotes. Multiple candidate C5-epimerases were found, suggesting that many more microorganisms are likely to exist possessing an L-iduronic acid residue as constituent of their cell wall polysaccharides
The Escherichia coli Serogroup O1 and O2 Lipopolysaccharides Are Encoded by Multiple O-antigen Gene Clusters
Escherichia coli strains belonging to serogroups O1 and O2 are frequently
associated with human infections, especially extra-intestinal infections such
as bloodstream infections or urinary tract infections. These strains can be
associated with a large array of flagellar antigens. Because of their
frequency and clinical importance, a reliable detection of E. coli O1 and O2
strains and also the frequently associated K1 capsule is important for
diagnosis and source attribution of E. coli infections in humans and animals.
By sequencing the O-antigen clusters of various O1 and O2 strains we showed
that the serogroups O1 and O2 are encoded by different sets of O-antigen
encoding genes and identified potentially new O-groups. We developed qPCR-
assays to detect the various O1 and O2 variants and the K1-encoding gene.
These qPCR assays proved to be 100% sensitive and 100% specific and could be
valuable tools for the investigations of zoonotic and food-borne infection of
humans with O1 and O2 extra-intestinal (ExPEC) or Shiga toxin-producing E.
coli (STEC) strains
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