3,055 research outputs found
Probabilities of spurious connections in gene networks: Application to expression time series
Motivation: The reconstruction of gene networks from gene expression
microarrays is gaining popularity as methods improve and as more data become
available. The reliability of such networks could be judged by the probability
that a connection between genes is spurious, resulting from chance fluctuations
rather than from a true biological relationship. Results: Unlike the false
discovery rate and positive false discovery rate, the decisive false discovery
rate (dFDR) is exactly equal to a conditional probability without assuming
independence or the randomness of hypothesis truth values. This property is
useful not only in the common application to the detection of differential gene
expression, but also in determining the probability of a spurious connection in
a reconstructed gene network. Estimators of the dFDR can estimate each of three
probabilities: 1. The probability that two genes that appear to be associated
with each other lack such association. 2. The probability that a time ordering
observed for two associated genes is misleading. 3. The probability that a time
ordering observed for two genes is misleading, either because they are not
associated or because they are associated without a lag in time. The first
probability applies to both static and dynamic gene networks, and the other two
only apply to dynamic gene networks. Availability: Cross-platform software for
network reconstruction, probability estimation, and plotting is free from
http://www.davidbickel.com as R functions and a Java application.Comment: Like q-bio.GN/0404032, this was rejected in March 2004 because it was
submitted to the math archive. The only modification is a corrected reference
to q-bio.GN/0404032, which was not modified at al
A Study of the Matrix Carleson Embedding Theorem with Applications to Sparse Operators
In this paper, we study the dyadic Carleson Embedding Theorem in the matrix
weighted setting. We provide two new proofs of this theorem, which highlight
connections between the matrix Carleson Embedding Theorem and both maximal
functions and -BMO duality. Along the way, we establish boundedness
results about new maximal functions associated to matrix weights and
duality results concerning and BMO sequence spaces in the matrix setting.
As an application, we then use this Carleson Embedding Theorem to show that if
is a sparse operator, then the operator norm of on satisfies:
for
every matrix weight .Comment: 14 page
Development of flight check-out system Final report
Flight checkout system breadboard design, construction and testin
Depletion forces near a soft surface
We investigate excluded-volume effects in a bidisperse colloidal suspension
near a flexible interface. Inspired by a recent experiment by Dinsmore et al.
(Phys. Rev, Lett. 80, 409 (1998)), we study the adsorption of a mesoscopic bead
on the surface and show that depletion forces could in principle lead to
particle encapsulation. We then consider the effect of surface fluctuations on
the depletion potential itself and construct the density profile of a polymer
solution near a soft interface. Surprisingly we find that the chains accumulate
at the wall, whereas the density displays a deficit of particles at distances
larger than the surface roughness. This non-monotonic behavior demonstrates
that surface fluctuations can have major repercusions on the properties of a
colloidal solution. On average, the additional contribution to the Gibbs
adsorbance is negative. The amplitude of the depletion potential between a
mesoscopic bead and the surface increases accordingly.Comment: 10 pages, 5 figure
Composite Effects of Polymorphisms near Multiple Regulatory Elements Create a Major-Effect QTL
Many agriculturally, evolutionarily, and medically important characters vary in a quantitative fashion. Unfortunately, the genes and sequence variants accounting for this variation remain largely unknown due to a variety of biological and technical challenges. Drosophila melanogaster contains high levels of sequence variation and low linkage disequilibrium, allowing us to dissect the effects of many causative variants within a single locus. Here, we take advantage of these features to identify and characterize the sequence polymorphisms that comprise major effect QTL alleles segregating at the bric-a-brac locus. We show that natural bric-a-brac alleles with large effects on cuticular pigmentation reflect a cumulative impact of polymorphisms that affect three functional regions: a promoter, a tissue-specific enhancer, and a Polycomb response element. Analysis of allele-specific expression at the bric-a-brac locus confirms that these polymorphisms modulate transcription at the cis-regulatory level. Our results establish that a single QTL can act through a confluence of multiple molecular mechanisms and that sequence variation in regions flanking experimentally validated functional elements can have significant quantitative effects on transcriptional activity and phenotype. These findings have important design and conceptual implications for basic and medical genomics
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