77 research outputs found
Characterization of ASR gene and its role in drought tolerance in chickpea (Cicer arietinum L.)
Chickpea has a profound nutritional and economic value in vegetarian society. Continuous
decline in chickpea productivity is attributed to insufficient genetic variability and different
environmental stresses. Chickpea like several other legumes is highly susceptible to terminal
drought stress. Multiple genes control drought tolerance and ASR gene plays a key role
in regulating different plant stresses. The present study describes the molecular characterization
and functional role of Abscissic acid and stress ripening (ASR) gene from chickpea
(Cicer arietinum) and the gene sequence identified was submitted to NCBI Genbank
(MK937569). Molecular analysis using MUSCLE software proved that the ASR nucleotide
sequences in different legumes show variations at various positions though ASR genes are
conserved in chickpea with only few variations. Sequence similarity of ASR gene to chickpea
putative ABA/WDS induced protein mRNA clearly indicated its potential involvement in
drought tolerance. Physiological screening and qRT-PCR results demonstrated increased
ASR gene expression under drought stress possibly enabled genotypes to perform better
under stress. Conserved domain search, protein structure analysis, prediction and validation,
network analysis using Phyre2, Swiss-PDB viewer, ProSA and STRING analysis
established the role of hypothetical ASR protein NP_001351739.1 in mediating drought
responses. NP_001351739.1 might have enhanced the ASR gene activity as a transcription
factor regulating drought stress tolerance in chickpea. This study could be useful in identification
of new ASR genes that play a major role in drought tolerance and also develop functional
markers for chickpea improvement
Plasma Wakefield Acceleration with a Modulated Proton Bunch
The plasma wakefield amplitudes which could be achieved via the modulation of
a long proton bunch are investigated. We find that in the limit of long bunches
compared to the plasma wavelength, the strength of the accelerating fields is
directly proportional to the number of particles in the drive bunch and
inversely proportional to the square of the transverse bunch size. The scaling
laws were tested and verified in detailed simulations using parameters of
existing proton accelerators, and large electric fields were achieved, reaching
1 GV/m for LHC bunches. Energy gains for test electrons beyond 6 TeV were found
in this case.Comment: 9 pages, 7 figure
Energy and system size dependence of \phi meson production in Cu+Cu and Au+Au collisions
We study the beam-energy and system-size dependence of \phi meson production
(using the hadronic decay mode \phi -- K+K-) by comparing the new results from
Cu+Cu collisions and previously reported Au+Au collisions at \sqrt{s_NN} = 62.4
and 200 GeV measured in the STAR experiment at RHIC. Data presented are from
mid-rapidity (|y|<0.5) for 0.4 < pT < 5 GeV/c. At a given beam energy, the
transverse momentum distributions for \phi mesons are observed to be similar in
yield and shape for Cu+Cu and Au+Au colliding systems with similar average
numbers of participating nucleons. The \phi meson yields in nucleus-nucleus
collisions, normalised by the average number of participating nucleons, are
found to be enhanced relative to those from p+p collisions with a different
trend compared to strange baryons. The enhancement for \phi mesons is observed
to be higher at \sqrt{s_NN} = 200 GeV compared to 62.4 GeV. These observations
for the produced \phi(s\bar{s}) mesons clearly suggest that, at these collision
energies, the source of enhancement of strange hadrons is related to the
formation of a dense partonic medium in high energy nucleus-nucleus collisions
and cannot be alone due to canonical suppression of their production in smaller
systems.Comment: 20 pages and 5 figure
Pion, kaon, proton and anti-proton transverse momentum distributions from p+p and d+Au collisions at GeV
Identified mid-rapidity particle spectra of , , and
from 200 GeV p+p and d+Au collisions are reported. A
time-of-flight detector based on multi-gap resistive plate chamber technology
is used for particle identification. The particle-species dependence of the
Cronin effect is observed to be significantly smaller than that at lower
energies. The ratio of the nuclear modification factor () between
protons and charged hadrons () in the transverse momentum
range GeV/c is measured to be
(stat)(syst) in minimum-bias collisions and shows little
centrality dependence. The yield ratio of in minimum-bias d+Au
collisions is found to be a factor of 2 lower than that in Au+Au collisions,
indicating that the Cronin effect alone is not enough to account for the
relative baryon enhancement observed in heavy ion collisions at RHIC.Comment: 6 pages, 4 figures, 1 table. We extended the pion spectra from
transverse momentum 1.8 GeV/c to 3. GeV/
Experimental and Theoretical Challenges in the Search for the Quark Gluon Plasma: The STAR Collaboration's Critical Assessment of the Evidence from RHIC Collisions
We review the most important experimental results from the first three years
of nucleus-nucleus collision studies at RHIC, with emphasis on results from the
STAR experiment, and we assess their interpretation and comparison to theory.
The theory-experiment comparison suggests that central Au+Au collisions at RHIC
produce dense, rapidly thermalizing matter characterized by: (1) initial energy
densities above the critical values predicted by lattice QCD for establishment
of a Quark-Gluon Plasma (QGP); (2) nearly ideal fluid flow, marked by
constituent interactions of very short mean free path, established most
probably at a stage preceding hadron formation; and (3) opacity to jets. Many
of the observations are consistent with models incorporating QGP formation in
the early collision stages, and have not found ready explanation in a hadronic
framework. However, the measurements themselves do not yet establish
unequivocal evidence for a transition to this new form of matter. The
theoretical treatment of the collision evolution, despite impressive successes,
invokes a suite of distinct models, degrees of freedom and assumptions of as
yet unknown quantitative consequence. We pose a set of important open
questions, and suggest additional measurements, at least some of which should
be addressed in order to establish a compelling basis to conclude definitively
that thermalized, deconfined quark-gluon matter has been produced at RHIC.Comment: 101 pages, 37 figures; revised version to Nucl. Phys.
Achievements and prospects of genomics-assisted breeding in three legume crops of the semi-arid tropics
Advances in next-generation sequencing and genotyping technologies have enabled generation of large-scale genomic resources such as molecular markers, transcript reads and BAC-end sequences (BESs) in chickpea, pigeonpea and groundnut, three major legume crops of the semi-arid tropics. Comprehensive transcriptome assemblies and genome sequences have either been developed or underway in these crops. Based on these resources, dense genetic maps, QTL maps as well as physical maps for these legume species have also been developed. As a result, these crops have graduated from ‘orphan’ or ‘less-studied’ crops to ‘genomic resources rich’ crops. This article summarizes above mentioned advances in genomics and genomics-assisted breeding applications in the form of marker-assisted selection (MAS) for hybrid purity assessment in pigeonpea; marker-assisted backcrossing (MABC) for introgressing QTL region for drought-tolerance related traits, Fusarium wilt (FW) resistance and Ascochyta blight (AB) resistance in chickpea; late leaf spot (LLS), leaf rust and nematode resistance in groundnut. We critically present the case of use of other modern breeding approaches like marker-assisted recurrent selection (MARS) and genomic selection (GS) to utilize the full potential of genomics-assisted breeding for developing superior cultivars with enhanced tolerance to various environmental stresses. In addition, this article recommends the use of advanced- backcross (AB-backcross) breeding and development of specialized populations such as multi-parents advanced generation intercross (MAGIC) for creating new variations that will help developing superior lines with broadened genetic base. In summary, we propose the use of integrated genomics and breeding approach in these legume crops to enhance crop productivity in marginal environments ensuring food security in developing countries
Azimuthal anisotropy in Au+Au collisions at √s\u3csub\u3eNN\u3c/sub\u3e = 200 GeV
The results from the STAR Collaboration on directed flow (ν1), elliptic flow (ν2), and the fourth harmonic (ν4) in the anisotropic azimuthal distribution of particles from Au+Au collisions at √sNN=200GeV are summarized and compared with results from other experiments and theoretical models. Results for identified particles are presented and fit with a blast-wave model. Different anisotropic flow analysis methods are compared and nonflow effects are extracted from the data. For ν2, scaling with the number of constituent quarks and parton coalescence are discussed. For ν4, scaling with v22 and quark coalescence are discussed
Minijet deformation and charge-independent angular correlations on momentum subspace (η,ϕ) in Au-Au collisions at √sNN=130 GeV
Measurements of two-particle correlations on angular difference variables η1−η2 (pseudorapidity) and ϕ1−ϕ2 (azimuth) are presented for all primary charged hadrons with transverse momentum 0.15≤pt≤2 GeV/c and |η|≤1.3 from Au-Au collisions at √sNN=130 GeV. Large-amplitude correlations are observed over a broad range in relative angles where distinct structures appear on the same-side and away-side (i.e., relative azimuth less than π/2 or greater than π/2). The principal correlation structures include that associated with elliptic flow plus a strong, same-side peak. It is hypothesized that the latter results from correlated hadrons associated with semi-hard parton scattering in the early stage of the heavy-ion collision which produces a jet-like correlation peak at small relative angles. The width of the jet-like peak on η1−η2 increases by a factor 2.3 from peripheral to central collisions, suggesting strong coupling of semi-hard scattered partons to a longitudinally-expanding medium. The new methods of jet analysis introduced here provide access to scattered partons at low transverse momentum well below the kinematic range where perturbative quantum chromodynamics and standard fragmentation models are applicable
Multiplicity dependence of inclusive p\u3csub\u3et\u3c/sub\u3e spectra from p−p collisions at √s = 200 GeV
We report measurements of transverse momentum pt spectra for ten event multiplicity classes of p−pcollisions at √s=200 GeV. By analyzing the multiplicity dependence we find that the spectrum shape can be decomposed into a part with amplitude proportional to multiplicity and described by a Lévy distribution on transverse mass mt, and a part with amplitude proportional to multiplicity squared and described by a Gaussian distribution on transverse rapidity yt. The functional forms of the two parts are nearly independent of event multiplicity. The two parts can be identified with the soft and hard components of a two-component model of p−p collisions. This analysis then provides the first isolation of the hard component of the pt spectrum as a distribution of simple form on yt
Identified hadron spectra at large transverse momentum in p+p and d+Au collisions at √sNN = 200 GeV
We present the transverse momentum (pT) spectra for identified charged pions, protons and anti-protons from p+p and d+Au collisions at . The spectra are measured around midrapidity (|y|/c with particle identification from the ionization energy loss and its relativistic rise in the time projection chamber and time-of-flight in STAR. The charged pion and proton + anti-proton spectra at high pT in p+p and d+Au collisions are in good agreement with a phenomenological model (EPOS) and with next-to-leading order perturbative quantum chromodynamic (NLO pQCD) calculations with a specific fragmentation scheme and factorization scale. We found that all proton, anti-proton and charged pion spectra in p+p collisions follow xT-scaling for the momentum range where particle production is dominated by hard processes (pT≳2 GeV/c). The nuclear modification factor around midrapidity is found to be greater than unity for charged pions and to be even larger for protons at 2T/c
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