49 research outputs found
Reference genome assembly for Australian Ascochyta rabiei Isolate ArME14
Ascochyta rabiei is the causal organism of ascochyta blight of chickpea and is present in chickpea crops worldwide. Here we report the release of a high-quality PacBio genome assembly for the Australian A. rabiei isolate ArME14. We compare the ArME14 genome assembly with an Illumina assembly for Indian A. rabiei isolate, ArD2. The ArME14 assembly has gapless sequences for nine chromosomes with telomere sequences at both ends and 13 large contig sequences that extend to one telomere. The total length of the ArME14 assembly was 40,927,385 bp, which was 6.26 Mb longer than the ArD2 assembly. Division of the genome by OcculterCut into GC-balanced and AT-dominant segments reveals 21% of the genome contains gene-sparse, AT-rich isochores. Transposable elements and repetitive DNA sequences in the ArME14 assembly made up 15% of the genome. A total of 11,257 protein-coding genes were predicted compared with 10,596 for ArD2. Many of the predicted genes missing from the ArD2 assembly were in genomic regions adjacent to AT-rich sequence. We compared the complement of predicted transcription factors and secreted proteins for the two A. rabiei genome assemblies and found that the isolates contain almost the same set of proteins. The small number of differences could represent real differences in the gene complement between isolates or possibly result from the different sequencing methods used. Prediction pipelines were applied for carbohydrate-active enzymes, secondary metabolite clusters and putative protein effectors. We predict that ArME14 contains between 450 and 650 CAZymes, 39 putative protein effectors and 26 secondary metabolite clusters
On The Pomeron at Large 't Hooft Coupling
We begin the process of unitarizing the Pomeron at large 't Hooft coupling.
We do so first in the conformal regime, which applies to good accuracy to a
number of real and toy problems in QCD. We rewrite the conformal Pomeron in the
-plane and transverse position space, and then work out the eikonal
approximation to multiple Pomeron exchange. This is done in the context of a
more general treatment of the complex -plane and the geometric consequences
of conformal invariance. The methods required are direct generalizations of our
previous work on single Pomeron exchange and on multiple graviton exchange in
AdS space, and should form a starting point for other investigations. We
consider unitarity and saturation in the conformal regime, noting elastic and
absorptive effects, and exploring where different processes dominate. Our
methods extend to confining theories and we briefly consider the Pomeron kernel
in this context. Though there is important model dependence that requires
detailed consideration, the eikonal approximation indicates that the Froissart
bound is generically both satisfied and saturated.Comment: 63 pages, 7 figures; published version: references updated and
several typos correcte
Dissipation from a heavy quark moving through N=4 super-Yang-Mills plasma
Using AdS/CFT, we compute the Fourier space profile of generated by
a heavy quark moving through a thermal plasma of strongly coupled N=4
super-Yang-Mills theory. We find evidence of a wake whose description includes
gauge fields with large momenta. We comment on the possible relevance of our
results to relativistic heavy ion collisions.Comment: 17 pages, 2 figures. v2: reference added, other minor improvements.
v3: improved the phrasing describing directional structure
On unquenched N=2 holographic flavor
The addition of fundamental degrees of freedom to a theory which is dual (at
low energies) to N=2 SYM in 1+3 dimensions is studied. The gauge theory lives
on a stack of Nc D5 branes wrapping an S^2 with the appropriate twist, while
the fundamental hypermultiplets are introduced by adding a different set of Nf
D5-branes. In a simple case, a system of first order equations taking into
account the backreaction of the flavor branes is derived (Nf/Nc is kept of
order 1). From it, the modification of the holomorphic coupling is computed
explicitly. Mesonic excitations are also discussed.Comment: 25 pages, 4 figure
Glueballs of Super Yang-Mills from Wrapped Branes
In this paper we study qualitative features of glueballs in N=1 SYM for
models of wrapped branes in IIA and IIB backgrounds. The scalar mode, 0++ is
found to be a mixture of the dilaton and the internal part of the metric. We
carry out the numerical study of the IIB background. The potential found
exhibits a mass gap and produces a discrete spectrum without any cut-off. We
propose a regularization procedure needed to make these states normalizable.Comment: 22 pages plus a appendixes, 2 figure
Energy Loss of Gluons, Baryons and k-Quarks in an N=4 SYM Plasma
We consider different types of external color sources that move through a
strongly-coupled thermal N=4 super-Yang-Mills plasma, and calculate, via the
AdS/CFT correspondence, the dissipative force (or equivalently, the rate of
energy loss) they experience. A bound state of k quarks in the totally
antisymmetric representation is found to feel a force with a nontrivial
k-dependence. Our result for k=1 (or k=N-1) agrees at large N with the one
obtained recently by Herzog et al. and Gubser, but contains in addition an
infinite series of 1/N corrections. The baryon (k=N) is seen to experience no
drag. Finally, a heavy gluon is found to be subject to a force which at large N
is twice as large as the one experienced by a heavy quark, in accordance with
gauge theory expectations.Comment: Latex 2e, 24 pages, 1 eps figure; v2: slightly amplified discussion
on the relation between the drag force and the tension of a spatial Wilson
loop; v3: minor changes, version to appear in JHE
A limiting velocity for quarkonium propagation in a strongly coupled plasma via AdS/CFT
We study the dispersion relations of mesons in a particular hot strongly
coupled supersymmetric gauge theory plasma. We find that at large momentum k
the dispersion relations become omega = v_0 k + a + b/k + ..., where the
limiting velocity v_0 is the same for mesons with any quantum numbers and
depends only on the ratio of the temperature to the quark mass T/m_q. We
compute a and b in terms of the meson quantum numbers and T/m_q. The limiting
meson velocity v_0 becomes much smaller than the speed of light at temperatures
below but close to T_diss, the temperature above which no meson bound states at
rest in the plasma are found. From our result for v_0, we find that the
temperature above which no meson bound states with velocity v exist is
T_diss(v) \simeq (1-v^2)^(1/4) T_diss, up to few percent corrections.We thus
confirm by direct calculation of meson dispersion relations a result inferred
indirectly in previous work via analysis of the screening length between a
static quark and antiquark in a moving plasma. Although we do not do our
calculations in QCD, we argue that the qualitative features of the dispersion
relation we compute, including in particular the relation between dissociation
temperature and meson velocity, may apply to bottomonium and charmonium mesons
propagating in the strongly coupled plasma of QCD. We discuss how our results
can contribute to understanding quarkonium physics in heavy ion collisions.Comment: 57 pages, 12 figures; references adde
Odderon in Gauge/String Duality
At high energies, elastic hadronic cross sections, such as , are dominated by vacuum exchange, which in leading order of
the expansion has been identified as the BFKL Pomeron or its strong AdS
dual the closed string Reggeized graviton \cite{Brower:2006ea}. However the
difference of particle anti-particle cross sections are given by a so-called
Odderon, carrying C = -1 vacuum quantum numbers identified in weak coupling
with odd numbers of exchanged gluons. Here we show that in the dual description
the Odderon is the Reggeized Kalb-Ramond field () in the
Neveu-Schwartz sector of closed string theory. To first order in strong
coupling, the high energy contribution of Odderon is evaluated for Super Yang-Mills by a generalization of the gravity dual analysis for
Pomeron in Ref. \cite{Brower:2006ea}. The consequence of confinement on the
Odderon are estimated in the confining QCD-like hardwall model of
Polchinski and Strassler \cite{Polchinski:2001tt}.Comment: 69 pages, 6 figures. Title change to better reflect the content of
the paper. More discussion added in the Comments section. To be published in
JHE
Holographic Duals of Quark Gluon Plasmas with Unquenched Flavors
We review the construction of gravitational solutions holographically dual to
N=1 quiver gauge theories with dynamical flavor multiplets. We focus on the
D3-D7 construction and consider the finite temperature, finite quark chemical
potential case where there is a charged black hole in the dual solution.
Discussed physical outputs of the model include its thermodynamics (with
susceptibilities) and general hydrodynamic properties.Comment: Lecture presented at the Workshop "AdS/CFT and Novel Approaches to
Hadron and Heavy Ion Physics", Kavli Institute of Theoretical Physics
(KITPC), Beijing, China, 13 October 2010. Review article to be published in
Communications in Theoretical Physics. 27 pages, 2 figure