219 research outputs found
Jet hadrochemistry as a characteristics of jet quenching
Jets produced in nucleus-nucleus collisions at the LHC are expected to be
strongly modified due to the interaction of the parton shower with the dense
QCD matter. Here, we point out that jet quenching can leave signatures not only
in the longitudinal and transverse jet energy and multiplicity distributions,
but also in the hadrochemical composition of the jet fragments. In particular,
we show that even in the absence of medium effects at or after hadronization,
the medium-modification of the parton shower can result in significant changes
in jet hadrochemistry. We discuss how jet hadrochemistry can be studied within
the high-multiplicity environment of nucleus-nucleus collisions at the LHC.Comment: 15 pages, 7 figures, LaTe
D-brane anti-D-brane effective action and brane interaction in open string channel
We construct the effective action of a -brane-anti--brane system by
making use of the non-abelian extension of tachyonic DBI action. We succeed the
construction by restricting the Chan-Paton factors of two non-BPS -branes
in the action to the Chan-Paton factors of a system. For the
special case that both branes are coincident, the action reduces to the one
proposed by A. Sen. \\The effective potential indicates that
when branes separation is larger than the string length scale, there are two
minima in the tachyon direction. As branes move toward each other under the
gravitational force, the tachyon tunneling from false to true vacuum may make a
bubble formation followed by a classical evolution of the bubble. On the other
hand, when branes separation is smaller than the string length scale, the
potential shows one maximum and one minimum. In this case, a homogeneous
tachyon rolling in real time makes an attractive potential for the branes
distance. This classical force is speculated to be the effective force between
the two branes.Comment: Latex, 14 pages, 1 figure, the version appears in JHE
Homologous Flares and Magnetic Field Topology in Active Region NOAA 10501 on 20 November 2003
We present and interpret observations of two morphologically homologous
flares that occurred in active region (AR) NOAA 10501 on 20 November 2003. Both
flares displayed four homologous H-alpha ribbons and were both accompanied by
coronal mass ejections (CMEs). The central flare ribbons were located at the
site of an emerging bipole in the center of the active region. The negative
polarity of this bipole fragmented in two main pieces, one rotating around the
positive polarity by ~ 110 deg within 32 hours. We model the coronal magnetic
field and compute its topology, using as boundary condition the magnetogram
closest in time to each flare. In particular, we calculate the location of
quasiseparatrix layers (QSLs) in order to understand the connectivity between
the flare ribbons. Though several polarities were present in AR 10501, the
global magnetic field topology corresponds to a quadrupolar magnetic field
distribution without magnetic null points. For both flares, the photospheric
traces of QSLs are similar and match well the locations of the four H-alpha
ribbons. This globally unchanged topology and the continuous shearing by the
rotating bipole are two key factors responsible for the flare homology.
However, our analyses also indicate that different magnetic connectivity
domains of the quadrupolar configuration become unstable during each flare, so
that magnetic reconnection proceeds differently in both events.Comment: 24 pages, 10 figures, Solar Physics (accepted
Demonstration of the temporal matter-wave Talbot effect for trapped matter waves
We demonstrate the temporal Talbot effect for trapped matter waves using
ultracold atoms in an optical lattice. We investigate the phase evolution of an
array of essentially non-interacting matter waves and observe matter-wave
collapse and revival in the form of a Talbot interference pattern. By using
long expansion times, we image momentum space with sub-recoil resolution,
allowing us to observe fractional Talbot fringes up to 10th order.Comment: 17 pages, 7 figure
Kaon Production and Kaon to Pion Ratio in Au+Au Collisions at \snn=130 GeV
Mid-rapidity transverse mass spectra and multiplicity densities of charged
and neutral kaons are reported for Au+Au collisions at \snn=130 GeV at RHIC.
The spectra are exponential in transverse mass, with an inverse slope of about
280 MeV in central collisions. The multiplicity densities for these particles
scale with the negative hadron pseudo-rapidity density. The charged kaon to
pion ratios are and
for the most central collisions. The ratio is lower than the same
ratio observed at the SPS while the is higher than the SPS result.
Both ratios are enhanced by about 50% relative to p+p and +p
collision data at similar energies.Comment: 6 pages, 3 figures, 1 tabl
Azimuthal anisotropy at RHIC: the first and fourth harmonics
We report the first observations of the first harmonic (directed flow, v_1),
and the fourth harmonic (v_4), in the azimuthal distribution of particles with
respect to the reaction plane in Au+Au collisions at the Relativistic Heavy Ion
Collider (RHIC). Both measurements were done taking advantage of the large
elliptic flow (v_2) generated at RHIC. From the correlation of v_2 with v_1 it
is determined that v_2 is positive, or {\it in-plane}. The integrated v_4 is
about a factor of 10 smaller than v_2. For the sixth (v_6) and eighth (v_8)
harmonics upper limits on the magnitudes are reported.Comment: 6 pages with 3 figures, as accepted for Phys. Rev. Letters The data
tables are at
http://www.star.bnl.gov/central/publications/pubDetail.php?id=3
Recurrence of nephrotic syndrome following kidney transplantation is associated with initial native kidney biopsy findings
Background and objectives: Steroid-resistant nephrotic syndrome (SRNS) due to focal segmental glomerulosclerosis (FSGS) and minimal change disease (MCD) is a leading cause of end-stage kidney disease in children. Recurrence of primary disease following transplantation is a major cause of allograft loss. The clinical determinants of disease recurrence are not completely known. Our objectives were to determine risk factors for recurrence of FSGS/MCD following kidney transplantation and factors that predict response to immunosuppression following recurrence. Methods: Multicenter study of pediatric patients with kidney transplants performed for ESKD due to SRNS between 1/2006 and 12/2015. Demographics, clinical course, and biopsy data were collected. Patients with primary-SRNS (PSRNS) were defined as those initially resistant to corticosteroid therapy at diagnosis, and patients with late-SRNS (LSRNS) as those initially responsive to steroids who subsequently developed steroid resistance. We performed logistic regression to determine risk factors associated with nephrotic syndrome (NS) recurrence. Results: We analyzed 158 patients; 64 (41%) had recurrence of NS in their renal allograft. Disease recurrence occurred in 78% of patients with LSRNS compared to 39% of those with PSRNS. Patients with MCD on initial native kidney biopsy had a 76% recurrence rate compared with a 40% recurrence rate in those with FSGS. Multivariable analysis showed that MCD histology (OR; 95% CI 5.6; 1.3–23.7) compared to FSGS predicted disease recurrence. Conclusions: Pediatric patients with MCD and LSRNS are at higher risk of disease recurrence following kidney transplantation. These findings may be useful for designing studies to test strategies for preventing recurrence
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