3,093 research outputs found
On similarity solutions of a boundary layer problem with an upstream moving wall
The problem of a boundary layer on a flat plate which has a constant velocity opposite in direction to that of the uniform mainstream is examined. It was previously shown that the solution of this boundary value problem is crucially dependent on the parameter which is the ratio of the velocity of the plate to the velocity of the free stream. In particular, it was proved that a solution exists only if this parameter does not exceed a certain critical value, and numerical evidence was adduced to show that this solution is nonunique. Using Crocco formulation the present work proves this nonuniqueness. Also considered are the analyticity of solutions and the derivation of upper bounds on the critical value of wall velocity parameter
Overcoming exponential volume scaling in quantum simulations of lattice gauge theories
Real-time evolution of quantum field theories using classical computers
requires resources that scale exponentially with the number of lattice sites.
Because of a fundamentally different computational strategy, quantum computers
can in principle be used to perform detailed studies of these dynamics from
first principles. Before performing such calculations, it is important to
ensure that the quantum algorithms used do not have a cost that scales
exponentially with the volume. In these proceedings, we present an interesting
test case: a formulation of a compact U(1) gauge theory in 2+1 dimensions free
of gauge redundancies. A naive implementation onto a quantum circuit has a gate
count that scales exponentially with the volume. We discuss how to break this
exponential scaling by performing an operator redefinition that reduces the
non-locality of the Hamiltonian. While we study only one theory as a test case,
it is possible that the exponential gate scaling will persist for formulations
of other gauge theories, including non-Abelian theories in higher dimensions.Comment: 11 pages, 2 figures, Proceedings of the 39th Annual International
Symposium on Lattice Field Theory (Lattice 2022), August 8-13 2022, Bonn,
German
A convergent algorithm for the hybrid problem of reconstructing conductivity from minimal interior data
We consider the hybrid problem of reconstructing the isotropic electric
conductivity of a body from interior Current Density Imaging data
obtainable using MRI measurements. We only require knowledge of the magnitude
of one current generated by a given voltage on the boundary
. As previously shown, the corresponding voltage potential u in
is a minimizer of the weighted least gradient problem
with . In this paper we present an
alternating split Bregman algorithm for treating such least gradient problems,
for non-negative and . We
give a detailed convergence proof by focusing to a large extent on the dual
problem. This leads naturally to the alternating split Bregman algorithm. The
dual problem also turns out to yield a novel method to recover the full vector
field from knowledge of its magnitude, and of the voltage on the
boundary. We then present several numerical experiments that illustrate the
convergence behavior of the proposed algorithm
THE VARIABLE GENOMIC ARCHITECTURE OF ISOLATION BETWEEN HYBRIDIZING SPECIES OF HOUSE MICE
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75350/1/EVO_846_sm_FigS3A.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/75350/2/EVO_846_sm_legend.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/75350/3/EVO_846_sm_FigS4.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/75350/4/j.1558-5646.2009.00846.x.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/75350/5/EVO_846_sm_FigS1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/75350/6/EVO_846_sm_FigS2.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/75350/7/EVO_846_sm_FigS3B.pd
Adaptive introgressive hybridization with the Algerian mouse (Mus spretus) promoted the evolution of anticoagulant rodenticide resistance in European house mice (M. musculus domesticus)
Song, Y., Endepols, S., Klemann, N., Richter, D., Matuschka, F.-R., Shih, C.-H., Nachman, M.W., Kohn, M.H
Induction of carcinoembryonic antigen expression in a three-dimensional culture system
MIP-101 is a poorly differentiated human colon carcinoma cell line established from ascites that produces minimal amounts of carcinoembryonic antigen (CEA), a 180 kDa glycoprotein tumor marker, and nonspecific cross-reacting antigen (NCA), a related protein that has 50 and 90 kDa isoforms, in vitro in monolayer culture. MIP-101 produces CEA when implanted into the peritoneum of nude mice but not when implanted into subcutaneous tissue. We tested whether MIP-101 cells may be induced to express CEA when cultured on microcarrier beads in three-dimensional cultures, either in static cultures as non-adherent aggregates or under dynamic conditions in a NASA-designed low shear stress bioreactor. MIP- 101 cells proliferated well under all three conditions and increased CEA and NCA production 3 - 4 fold when grown in three-dimensional cultures compared to MIP-101 cells growing logarithmically in monolayers. These results suggest that three-dimensional growth in vitro simulates tumor function in vivo and that three-dimensional growth by itself may enhance production of molecules that are associated with the metastatic process
The Machine Learning Landscape of Top Taggers
Based on the established task of identifying boosted, hadronically decaying
top quarks, we compare a wide range of modern machine learning approaches.
Unlike most established methods they rely on low-level input, for instance
calorimeter output. While their network architectures are vastly different,
their performance is comparatively similar. In general, we find that these new
approaches are extremely powerful and great fun.Comment: Yet another tagger included
The Genomic Architecture of Population Divergence between Subspecies of the European Rabbit
The analysis of introgression of genomic regions between divergent populations provides an excellent opportunity to
determine the genetic basis of reproductive isolation during the early stages of speciation. However, hybridization and
subsequent gene flow must be relatively common in order to localize individual loci that resist introgression. In this study,
we used next-generation sequencing to study genome-wide patterns of genetic differentiation between two hybridizing
subspecies of rabbits (Oryctolagus cuniculus algirus and O. c. cuniculus) that are known to undergo high rates of gene
exchange. Our primary objective was to identify specific genes or genomic regions that have resisted introgression and are
likely to confer reproductive barriers in natural conditions. On the basis of 326,000 polymorphisms, we found low to
moderate overall levels of differentiation between subspecies, and fewer than 200 genomic regions dispersed throughout
the genome showing high differentiation consistent with a signature of reduced gene flow. Most differentiated regions
were smaller than 200 Kb and contained very few genes. Remarkably, 30 regions were each found to contain a single gene,
facilitating the identification of candidate genes underlying reproductive isolation. This gene-level resolution yielded several
insights into the genetic basis and architecture of reproductive isolation in rabbits. Regions of high differentiation were
enriched on the X-chromosome and near centromeres. Genes lying within differentiated regions were often associated with
transcription and epigenetic activities, including chromatin organization, regulation of transcription, and DNA binding.
Overall, our results from a naturally hybridizing system share important commonalities with hybrid incompatibility genes
identified using laboratory crosses in mice and flies, highlighting general mechanisms underlying the maintenance of
reproductive barriers
Limiting Carleman weights and anisotropic inverse problems
In this article we consider the anisotropic Calderon problem and related
inverse problems. The approach is based on limiting Carleman weights,
introduced in Kenig-Sjoestrand-Uhlmann (Ann. of Math. 2007) in the Euclidean
case. We characterize those Riemannian manifolds which admit limiting Carleman
weights, and give a complex geometrical optics construction for a class of such
manifolds. This is used to prove uniqueness results for anisotropic inverse
problems, via the attenuated geodesic X-ray transform. Earlier results in
dimension were restricted to real-analytic metrics.Comment: 58 page
- …