121,879 research outputs found
On the Clifford-Fourier transform
For functions that take values in the Clifford algebra, we study the
Clifford-Fourier transform on defined with a kernel function , replacing the kernel
of the ordinary Fourier transform, where . An explicit formula of
is derived, which can be further simplified to a finite sum of Bessel
functions when is even. The closed formula of the kernel allows us to study
the Clifford-Fourier transform and prove the inversion formula, for which a
generalized translation operator and a convolution are defined and used.Comment: Some small changes, 30 pages, accepted for publication in IMR
Low dimensional cohomology of general conformal algebras
We compute the low dimensional cohomologies ,
H^q(gc_N,\C) of the infinite rank general Lie conformal algebras with
trivial coefficients for or . We also prove that the
cohomology of with coefficients in its natural module is trivial, i.e.,
H^*(gc_N,\C[\ptl]^N)=0; thus partially solve an open problem of
Bakalov-Kac-Voronov in [{\it Comm. Math. Phys.,} {\bf200} (1999), 561-598].Comment: 18 page
Making sense o fhormone-mediated defense networking: from rice to Arabidopsis
Phytohormones are not only essential for plant growth and development but also play central roles in triggering the plant immune signaling network. Historically, research aimed at elucidating the defense-associated role of hormones has tended to focus on the use of experimentally tractable dicot plants such as Arabidopsis thaliana. Emerging from these studies is a picture whereby complex crosstalk and induced hormonal changes mold plant health and disease, with outcomes largely dependent on the lifestyle and infection strategy of invading pathogens. However, recent studies in monocot plants are starting to provide additional important insights into the immune-regulatory roles of hormones, often revealing unique complexities. In this review, we address the latest discoveries dealing with hormone-mediated immunity in rice, one of the most important food crops and an excellent model for molecular genetic studies in monocots. Moreover, we highlight interactions between hormone signaling, rice defense and pathogen virulence, and discuss the differences and similarities with findings in Arabidopsis. Finally, we present a model for hormone defense networking in rice and describe how detailed knowledge of hormone crosstalk mechanisms can be used for engineering durable rice disease resistance
Edge States and Quantum Hall Effect in Graphene under a Modulated Magnetic Field
Graphene properties can be manipulated by a periodic potential. Based on the
tight-binding model, we study graphene under a one-dimensional (1D) modulated
magnetic field which contains both a uniform and a staggered component. New
chiral current-carrying edge states are generated at the interfaces where the
staggered component changes direction. These edge states lead to an unusual
integer quantum Hall effect (QHE) in graphene, which can be observed
experimentally by a standard four-terminal Hall measurement. When Zeeman spin
splitting is considered, a novel state is predicted where the electron edge
currents with opposite polarization propagate in the opposite directions at one
sample boundary, whereas propagate in the same directions at the other sample
boundary.Comment: 5 pages, 4 figure
An updated catalog of M31 globular-like clusters: UBVRI photometry, ages, and masses
We present an updated UBVRI photometric catalog containing 970 objects in the
field of M31, selected from the Revised Bologna Catalog (RBC v.4.0), including
965, 967, 965, 953, and 827 sources in the individual UBVRI bands,
respectively, of which 205, 123, 14, 126, and 109 objects do not have
previously published photometry. Photometry is performed using archival images
from the Local Group Galaxies Survey, which covers 2.2 deg^2 along the major
axis of M31. We focus on 445 confirmed `globular-like' clusters and candidates,
comprising typical globular and young massive clusters. The ages and masses of
these objects are derived by comparison of their observed spectral-energy
distributions with simple stellar population synthesis. Approximately half of
the clusters are younger than 2 Gyr, suggesting that there has been significant
recent active star formation in M31, which is consistent with previous results.
We note that clusters in the halo (r_ projected>30kpc) are composed of two
different components, older clusters with ages >10 Gyr and younger clusters
with ages around 1 Gyr. The spatial distributions show that the young clusters
(<2 Gyr) are spatially coincident with the galaxy's disk, including the `10 kpc
ring,' the `outer ring,' and the halo of M31, while the old clusters (> 2 Gyr)
are spatially correlated with the bulge and halo. We also estimate the masses
of the 445 confirmed clusters and candidates in M31 and find that our estimates
agree well with previously published values. We find that none of the young
disk clusters can survive the inevitable encounters with giant molecular clouds
in the galaxy's disk and that they will eventually disrupt on timescales of a
few Gyr. Specifically, young disk clusters with a mass of 10^4 M_\odot are
expected to dissolve within 3.0 Gyr and will, thus, not evolve to become
globular clusters.Comment: 35 pages, 20 figures and 5 tables, accepted for publication in Ap
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