1,189 research outputs found
On the Distribution of Generating Functions
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135518/1/blms0113.pd
Nuclear Condensations of Furan
In connection with studies on orientation of furan and the synthesis of beta-substituted furans, condensation reactions have been effected with diazomethane, aryl-diazonium compounds, diazoacetic ester and related types with furan and its derivatives. The condensations in some cases are preceded by 1,2- and 1,4- additions. It appears that the difficulty in preparing simple furan-diazonium compounds is due, in part, to the ready coupling reaction of the diazonium group with the furan nucleus
Spin torque, tunnel-current spin polarization and magnetoresistance in MgO magnetic tunnel junctions
We examine the spin torque (ST) response of magnetic tunnel junctions (MTJs)
with ultra-thin MgO tunnel barrier layers to investigate the relationship
between the spin-transfer torque and the tunnel magnetoresistance (TMR) under
finite bias. We find that the spin torque per unit current exerted on the free
layer decreases by less than 10% over a bias range where the TMR decreases by
over 40%. We examine the implications of this result for various spin-polarized
tunneling models and find that it is consistent with magnetic-state-dependent
effective tunnel decay lengths.Comment: 4 pages, 3 figure
Sums of two squares and a power
We extend results of Jagy and Kaplansky and the present authors and show that
for all there are infinitely many positive integers , which cannot
be written as for positive integers , where for
a congruence condition is imposed on . These
examples are of interest as there is no congruence obstruction itself for the
representation of these . This way we provide a new family of
counterexamples to the Hasse principle or strong approximation.Comment: 6 pages, to appear in the memorial volume "From Arithmetic to
Zeta-Functions - Number Theory in Memory of Wolfgang Schwarz
The Missouri soil saving dam : low-cost structure for use in farm plans for water management
Cover title."A revision of Bulletin 434" -- P. [3]
Scaling metagenome sequence assembly with probabilistic de Bruijn graphs
Deep sequencing has enabled the investigation of a wide range of
environmental microbial ecosystems, but the high memory requirements for {\em
de novo} assembly of short-read shotgun sequencing data from these complex
populations are an increasingly large practical barrier. Here we introduce a
memory-efficient graph representation with which we can analyze the k-mer
connectivity of metagenomic samples. The graph representation is based on a
probabilistic data structure, a Bloom filter, that allows us to efficiently
store assembly graphs in as little as 4 bits per k-mer, albeit inexactly. We
show that this data structure accurately represents DNA assembly graphs in low
memory. We apply this data structure to the problem of partitioning assembly
graphs into components as a prelude to assembly, and show that this reduces the
overall memory requirements for {\em de novo} assembly of metagenomes. On one
soil metagenome assembly, this approach achieves a nearly 40-fold decrease in
the maximum memory requirements for assembly. This probabilistic graph
representation is a significant theoretical advance in storing assembly graphs
and also yields immediate leverage on metagenomic assembly
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