148 research outputs found
The molecular basis of beta-thalassemia intermedia in southern China: genotypic heterogeneity and phenotypic diversity
<p>Abstract</p> <p>Background</p> <p>The clinical syndrome of thalassemia intermedia (TI) results from the β-globin genotypes in combination with factors to produce fetal haemoglobin (HbF) and/or co-inheritance of α-thalassemia. However, very little is currently known of the molecular basis of Chinese TI patients.</p> <p>Methods</p> <p>We systematically analyzed and characterized β-globin genotypes, α-thalassemia determinants, and known primary genetic modifiers linked to the production of HbF and the aggravation of α/β imbalance in 117 Chinese TI patients. Genotype-phenotype correlations were analyzed based on retrospective clinical observations.</p> <p>Results</p> <p>A total of 117 TI patients were divided into two major groups, namely heterozygous β-thalassemia (n = 20) in which 14 were characterized as having a mild TI with the Hb levels of 68-95 g/L except for five co-inherited ααα<sup>anti-3.7 </sup>triplication and one carried a dominant mutation; and β-thalassemia homozygotes or compound heterozygotes for β-thalassemia and other β-globin defects in which the β<sup>+</sup>-thalassemia mutation was the most common (49/97), hemoglobin E (HbE) variants was second (27/97), and deletional hereditary persistence of fetal hemoglobin (HPFH) or δβ-thalassemia was third (11/97). Two novel mutations, Term CD+32(A→C) and Cap+39(C→T), have been detected.</p> <p>Conclusions</p> <p>Chinese TI patients showed considerable heterogeneity, both phenotypically and genotypically. The clinical outcomes of our TI patients were mostly explained by the genotypes linked to the β- and α-globin gene cluster. However, for a group of 14 patients (13 β<sup>0</sup>/β<sup>N </sup>and 1 β<sup>+</sup>/β<sup>N</sup>) with known heterozygous mutations of β-thalassemia and three with homozygous β-thalassemia (β<sup>0</sup>/β<sup>0</sup>), the existence of other causative genetic determinants is remaining to be molecularly defined.</p
Studies of di-jet survival and surface emission bias in Au+Au collisions via angular correlations with respect to back-to-back leading hadrons
We report first results from an analysis based on a new multi-hadron
correlation technique, exploring jet-medium interactions and di-jet surface
emission bias at RHIC. Pairs of back-to-back high transverse momentum hadrons
are used for triggers to study associated hadron distributions. In contrast
with two- and three-particle correlations with a single trigger with similar
kinematic selections, the associated hadron distribution of both trigger sides
reveals no modification in either relative pseudo-rapidity or relative
azimuthal angle from d+Au to central Au+Au collisions. We determine associated
hadron yields and spectra as well as production rates for such correlated
back-to-back triggers to gain additional insights on medium properties.Comment: By the STAR Collaboration. 6 pages, 2 figure
System size and energy dependence of near-side di-hadron correlations
Two-particle azimuthal () and pseudorapidity ()
correlations using a trigger particle with large transverse momentum () in
+Au, Cu+Cu and Au+Au collisions at =\xspace 62.4 GeV and
200~GeV from the STAR experiment at RHIC are presented. The \ns correlation is
separated into a jet-like component, narrow in both and
, and the ridge, narrow in but broad in .
Both components are studied as a function of collision centrality, and the
jet-like correlation is studied as a function of the trigger and associated
. The behavior of the jet-like component is remarkably consistent for
different collision systems, suggesting it is produced by fragmentation. The
width of the jet-like correlation is found to increase with the system size.
The ridge, previously observed in Au+Au collisions at = 200
GeV, is also found in Cu+Cu collisions and in collisions at
=\xspace 62.4 GeV, but is found to be substantially smaller at
=\xspace 62.4 GeV than at = 200 GeV for the
same average number of participants ().
Measurements of the ridge are compared to models.Comment: 17 pages, 14 figures, submitted to Phys. Rev.
Measurements of Dihadron Correlations Relative to the Event Plane in Au+Au Collisions at GeV
Dihadron azimuthal correlations containing a high transverse momentum (\pt)
trigger particle are sensitive to the properties of the nuclear medium created
at RHIC through the strong interactions occurring between the traversing parton
and the medium, i.e. jet-quenching. Previous measurements revealed a strong
modification to dihadron azimuthal correlations in Au+Au collisions with
respect to \pp\ and \dAu\ collisions. The modification increases with the
collision centrality, suggesting a path-length dependence to the jet-quenching
effect. This paper reports STAR measurements of dihadron azimuthal correlations
in mid-central (20-60\%) Au+Au collisions at \snn=200~GeV as a function of
the trigger particle's azimuthal angle relative to the event plane,
\phis=|\phit-\psiEP|. The azimuthal correlation is studied as a function of
both the trigger and associated particle \pt. The subtractions of the
combinatorial background and anisotropic flow, assuming Zero Yield At Minimum
(\zyam), are described. The away-side correlation is strongly modified, and the
modification varies with \phis, which is expected to be related to the
path-length that the away-side parton traverses. The pseudo-rapidity (\deta)
dependence of the near-side correlation, sensitive to long range \deta
correlations (the ridge), is also investigated. The ridge and jet-like
components of the near-side correlation are studied as a function of \phis.
The ridge appears to drop with increasing \phis while the jet-like component
remains approximately constant. ...Comment: 50 pages, 39 figures, 6 table
Observation of the antimatter helium-4 nucleus
High-energy nuclear collisions create an energy density similar to that of
the universe microseconds after the Big Bang, and in both cases, matter and
antimatter are formed with comparable abundance. However, the relatively
short-lived expansion in nuclear collisions allows antimatter to decouple
quickly from matter, and avoid annihilation. Thus, a high energy accelerator of
heavy nuclei is an efficient means of producing and studying antimatter. The
antimatter helium-4 nucleus (), also known as the anti-{\alpha}
(), consists of two antiprotons and two antineutrons (baryon
number B=-4). It has not been observed previously, although the {\alpha}
particle was identified a century ago by Rutherford and is present in cosmic
radiation at the 10% level. Antimatter nuclei with B < -1 have been observed
only as rare products of interactions at particle accelerators, where the rate
of antinucleus production in high-energy collisions decreases by about 1000
with each additional antinucleon. We present the observation of the antimatter
helium-4 nucleus, the heaviest observed antinucleus. In total 18
counts were detected at the STAR experiment at RHIC in 10 recorded Au+Au
collisions at center-of-mass energies of 200 GeV and 62 GeV per nucleon-nucleon
pair. The yield is consistent with expectations from thermodynamic and
coalescent nucleosynthesis models, which has implications beyond nuclear
physics.Comment: 19 pages, 4 figures. Submitted to Nature. Under media embarg
Measurements of and Production in + Collisions at = 200 GeV
We report measurements of charmed-hadron (, ) production cross
sections at mid-rapidity in + collisions at a center-of-mass energy of
200 GeV by the STAR experiment. Charmed hadrons were reconstructed via the
hadronic decays , and their charge conjugates,
covering the range of 0.62.0 GeV/ and 2.06.0 GeV/ for
and , respectively. From this analysis, the charm-pair production cross
section at mid-rapidity is = 170 45
(stat.) (sys.) b. The extracted charm-pair cross section is
compared to perturbative QCD calculations. The transverse momentum differential
cross section is found to be consistent with the upper bound of a Fixed-Order
Next-to-Leading Logarithm calculation.Comment: 15 pages, 16 figures. Revised version submitted to Phys. Rev.
Identified hadron compositions in p+p and Au+Au collisions at high transverse momenta at GeV
We report transverse momentum ( GeV/) spectra of , , , ,
, and at mid-rapidity in p+p and Au+Au collisions at
= 200 GeV. Perturbative QCD calculations are consistent with
spectra in p+p collisions but do not reproduce and
spectra. The observed decreasing antiparticle-to-particle ratios with
increasing provide experimental evidence for varying quark and gluon jet
contributions to high- hadron yields. The relative hadron abundances in
Au+Au at GeV/ are measured to be similar to the p+p
results, despite the expected Casimir effect for parton energy loss.Comment: 6 pages, 3 figures, published at PR
An Experimental Exploration of the QCD Phase Diagram: The Search for the Critical Point and the Onset of De-confinement
The QCD phase diagram lies at the heart of what the RHIC Physics Program is
all about. While RHIC has been operating very successfully at or close to its
maximum energy for almost a decade, it has become clear that this collider can
also be operated at lower energies down to 5 GeV without extensive upgrades. An
exploration of the full region of beam energies available at the RHIC facility
is imperative. The STAR detector, due to its large uniform acceptance and
excellent particle identification capabilities, is uniquely positioned to carry
out this program in depth and detail. The first exploratory beam energy scan
(BES) run at RHIC took place in 2010 (Run 10), since several STAR upgrades,
most importantly a full barrel Time of Flight detector, are now completed which
add new capabilities important for the interesting physics at BES energies. In
this document we discuss current proposed measurements, with estimations of the
accuracy of the measurements given an assumed event count at each beam energy.Comment: 59 pages, 78 figure
9p21 loss confers a cold tumor immune microenvironment and primary resistance to immune checkpoint therapy
Immune checkpoint therapy (ICT) provides substantial clinical benefits to cancer patients, but a large proportion of cancers do not respond to ICT. To date, the genomic underpinnings of primary resistance to ICT remain elusive. Here, we performed immunogenomic analysis of data from TCGA and clinical trials of anti-PD-1/PD-L1 therapy, with a particular focus on homozygous deletion of 9p21.3 (9p21 loss), one of the most frequent genomic defects occurring in ~13% of all cancers. We demonstrate that 9p21 loss confers "cold" tumor-immune phenotypes, characterized by reduced abundance of tumor-infiltrating leukocytes (TILs), particularly, T/B/NK cells, altered spatial TILs patterns, diminished immune cell trafficking/activation, decreased rate of PD-L1 positivity, along with activation of immunosuppressive signaling. Notably, patients with 9p21 loss exhibited significantly lower response rates to ICT and worse outcomes, which were corroborated in eight ICT trials of >1,000 patients. Further, 9p21 loss synergizes with PD-L1/TMB for patient stratification. A "response score" was derived by incorporating 9p21 loss, PD-L1 expression and TMB levels in pre-treatment tumors, which outperforms PD-L1, TMB, and their combination in identifying patients with high likelihood of achieving sustained response from otherwise non-responders. Moreover, we describe potential druggable targets in 9p21-loss tumors, which could be exploited to design rational therapeutic interventions
Inclusive charged hadron elliptic flow in Au + Au collisions at = 7.7 - 39 GeV
A systematic study is presented for centrality, transverse momentum ()
and pseudorapidity () dependence of the inclusive charged hadron elliptic
flow () at midrapidity() in Au+Au collisions at
= 7.7, 11.5, 19.6, 27 and 39 GeV. The results obtained with
different methods, including correlations with the event plane reconstructed in
a region separated by a large pseudorapidity gap and 4-particle cumulants
(), are presented in order to investigate non-flow correlations and
fluctuations. We observe that the difference between and
is smaller at the lower collision energies. Values of , scaled by
the initial coordinate space eccentricity, , as a function
of are larger in more central collisions, suggesting stronger collective
flow develops in more central collisions, similar to the results at higher
collision energies. These results are compared to measurements at higher
energies at the Relativistic Heavy Ion Collider ( = 62.4 and 200
GeV) and at the Large Hadron Collider (Pb + Pb collisions at =
2.76 TeV). The values for fixed rise with increasing collision
energy within the range studied (). A comparison to
viscous hydrodynamic simulations is made to potentially help understand the
energy dependence of . We also compare the results to UrQMD
and AMPT transport model calculations, and physics implications on the
dominance of partonic versus hadronic phases in the system created at Beam
Energy Scan (BES) energies are discussed.Comment: 20 pages, 12 figures. Version accepted by PR
- …