505 research outputs found
Dynamical Computation on Coefficients of Electroweak Chiral Lagrangian from One-doublet and Topcolor-assisted Technicolor Models
Based on previous studies deriving the chiral Lagrangian for pseudo scalar
mesons from the first principle of QCD, we derive the electroweak chiral
Lagrangian and build up a formulation for computing its coefficients from
one-doublet technicolor model and a schematic topcolor-assisted technicolor
model. We find that the coefficients of the electroweak chiral Lagrangian for
the topcolor-assisted technicolor model are divided into three parts: direct
TC2 interaction part, TC1 and TC2 induced effective Z' particle contribution
part, and ordinary quarks contribution part. The first two parts are computed
in this paper and we show that the direct TC2 interaction part is the same as
that in the one-doublet technicolor model, while effective Z' contributions are
at least proportional to the p^2 order parameter \beta_1 in the electroweak
chiral Lagrangian and typical features of topcolor-assisted technicolor model
are that it only allows positive T and U parameters and the T parameter varies
in the range 0\sim 1/(25\alpha), the upper bound of T parameter will decrease
as long as Z' mass become large. The S parameter can be either positive or
negative depending on whether the Z' mass is large or small. The Z' mass is
also bounded above and the upper bound depend on value of T parameter. We
obtain the values for all the coefficients of the electroweak chiral Lagrangian
up to order of p^4.Comment: 52 pages, 15 figure
Accurate Segmentation of CT Male Pelvic Organs via Regression-Based Deformable Models and Multi-Task Random Forests
Segmenting male pelvic organs from CT images is a prerequisite for prostate cancer radiotherapy. The efficacy of radiation treatment highly depends on segmentation accuracy. However, accurate segmentation of male pelvic organs is challenging due to low tissue contrast of CT images, as well as large variations of shape and appearance of the pelvic organs. Among existing segmentation methods, deformable models are the most popular, as shape prior can be easily incorporated to regularize the segmentation. Nonetheless, the sensitivity to initialization often limits their performance, especially for segmenting organs with large shape variations. In this paper, we propose a novel approach to guide deformable models, thus making them robust against arbitrary initializations. Specifically, we learn a displacement regressor, which predicts 3D displacement from any image voxel to the target organ boundary based on the local patch appearance. This regressor provides a nonlocal external force for each vertex of deformable model, thus overcoming the initialization problem suffered by the traditional deformable models. To learn a reliable displacement regressor, two strategies are particularly proposed. 1) A multi-task random forest is proposed to learn the displacement regressor jointly with the organ classifier; 2) an auto-context model is used to iteratively enforce structural information during voxel-wise prediction. Extensive experiments on 313 planning CT scans of 313 patients show that our method achieves better results than alternative classification or regression based methods, and also several other existing methods in CT pelvic organ segmentation
The influence of net-quarks on the yields and rapidity spectra of identified hadrons
Within a quark combination model, we study systematically the yields and
rapidity spectra of various hadrons in central Au+Au collisions at
GeV. We find that considering the difference in rapidity
between net-quarks and newborn quarks, the data of multiplicities, rapidity
distributions for , , and, in particular the
ratios of charged antihadron to hadron as a function of rapidity, can be well
described. The effect of net-quarks on various hadrons is analysed, and the
rapidity distributions for , ,
, ()
and are predicted. We discuss
the rapidity distribution of net-baryon, and find that it reflects exactly the
energy loss of colliding nuclei.Comment: 8 pages, 7 figure
Centrality dependence of spectra for identified hadrons in Au+Au and Cu+Cu collisions at GeV
The centrality dependence of transverse momentum spectra for identified
hadrons at midrapidity in Au+Au collisions at GeV is
systematically studied in a quark combination model. The
spectra of , , and in
different centrality bins and the nuclear modification factors () for
these hadrons are calculated. The centrality dependence of the average
collective transverse velocity for the hot and dense quark matter
is obtained in Au+Au collisions, and it is applied to a relative smaller Cu+Cu
collision system. The centrality dependence of spectra and
the for , and in Cu+Cu collisions at
GeV are well described. The results show that is only a function of the number of participants and it is
independent of the collision system.Comment: 7 pages, 6 figure
Rapidity dependence of hadron production in central Au+Au collisions at GeV
The rapidity and transverse momentum spectra for identified hadrons in
central Au+Au collisions at GeV are computed in a quark
combination model. The data of rapidity distributions for ,
, and net protons are well described. We
also predict rapidity distributions for , ,
() and
. The multiplicity ratios of
charged antihadrons to hadrons as a function of rapidity are reproduced. The
results for spectra of , , and for
the ratios in a broader range agree well with the data.
Finally the rapidity dependence of transverse momentum distributions for
hadrons are given.Comment: 10 pages,11figures,3 table
Prostate deformation from inflatable rectal probe cover and dosimetric effects in prostate seed implant brachytherapy: Deformation on prostate permanent brachytherapy dosimetry
Prostate brachytherapy is an important treatment technique for patients with localized prostate cancer. An inflatable rectal ultrasound probe cover is frequently utilized during the procedure to adjust for unfavorable prostate position relative to the implant grid. However, the inflated cover causes prostate deformation, which is not accounted for during dosimetric planning. Most of the therapeutic dose is delivered after the procedure when the prostate and surrounding organs-at-risk are less deformed. The aim of this study is to quantify the potential dosimetry changes between the initial plan (prostate deformed) and the more realistic dosimetry when the prostate is less deformed without the cover
Self-Transforming Configuration Based on Atmospheric-Adaptive Materials for Solid Oxide Cells
Solid oxide cells (SOC) with a symmetrical configuration have been focused due to the practical benefits of such configurations, such as minimized compatibility issues, a simple fabrication process and reduced cost compared to SOCs with the asymmetrical configuration. However, the performance of SOCs using a single type of electrode material (symmetrical configuration) is lower than the performance of those using the dissimilar electrode materials (asymmetrical configuration). Therefore, to achieve a high-performance cell, we design a 'self-transforming cell' with the asymmetric configuration using only materials of the single type, one based on atmospheric adaptive materials. Atmospheric-adaptive perovskite Pr0.5Ba0.5Mn0.85Co0.15O3-delta (PBMCo) was used for the so-called self-transforming cell electrodes, which changed to layered perovskite and metal in the fuel atmosphere and retained its original structure in the air atmosphere. In fuel cell mods, the self-transforming cell shows excellent electrochemical performance of 1.10Wcm(-2) at 800 degrees C and good stability for 100 h without any catalyst. In electrolysis mode, the moderate current densities of -0.42A cm(-2) for 3 vol.% H2O and -0.62 A cm(-2) for 10 vol.% H2O, respectively, were observed at a cell voltage of 1.3V at 800 degrees C. In the reversible cycling test, the transforming cell maintains the constant voltages for 30 h at +/- 0.2A cm(-2) under 10 vol. % H2O
Search for Production via Trilepton Final States in collisions at TeV
We have searched for associated production of the lightest chargino,
, and next-to-lightest neutralino, , of the
Minimal Supersymmetric Standard Model in collisions at
\mbox{ = 1.8 TeV} using the \D0 detector at the Fermilab Tevatron
collider. Data corresponding to an integrated luminosity of 12.5 \ipb
were examined for events containing three isolated leptons. No evidence for
pair production was found. Limits on
BrBr are
presented.Comment: 17 pages (13 + 1 page table + 3 pages figures). 3 PostScript figures
will follow in a UUEncoded, gzip'd, tar file. Text in LaTex format. Submitted
to Physical Review Letters. Replace comments - Had to resumbmit version with
EPSF directive
IDN2 and Its Paralogs Form a Complex Required for RNA–Directed DNA Methylation
IDN2/RDM12 has been previously identified as a component of the RNA–directed DNA methylation (RdDM) machinery in Arabidopsis thaliana, but how it functions in RdDM remains unknown. By affinity purification of IDN2, we co-purified two IDN2 paralogs IDP1 and IDP2 (IDN2 PARALOG 1 and 2). The coiled-coil domain between the XS and XH domains of IDN2 is essential for IDN2 homodimerization, whereas the IDN2 C-terminal XH domain but not the coiled-coil domain is required for IDN2 interaction with IDP1 and IDP2. By introducing the wild-type IDN2 sequence and its mutated derivatives into the idn2 mutant for complementation testing, we demonstrated that the previously uncharacterized IDN2 XH domain is required for the IDN2-IDP1/IDP2 complex formation as well as for IDN2 function. IDP1 is required for de novo DNA methylation, siRNA accumulation, and transcriptional gene silencing, whereas IDP2 has partially overlapping roles with IDP1. Unlike IDN2, IDP1 and IDP2 are incapable of binding double-stranded RNA, suggesting that the roles of IDP1 and IDP2 are different from those of IDN2 in the IDN2-IDP1/IDP2 complex and that IDP1 and IDP2 are essential for the functioning of the complex in RdDM
Challenges in QCD matter physics - The Compressed Baryonic Matter experiment at FAIR
Substantial experimental and theoretical efforts worldwide are devoted to
explore the phase diagram of strongly interacting matter. At LHC and top RHIC
energies, QCD matter is studied at very high temperatures and nearly vanishing
net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was
created at experiments at RHIC and LHC. The transition from the QGP back to the
hadron gas is found to be a smooth cross over. For larger net-baryon densities
and lower temperatures, it is expected that the QCD phase diagram exhibits a
rich structure, such as a first-order phase transition between hadronic and
partonic matter which terminates in a critical point, or exotic phases like
quarkyonic matter. The discovery of these landmarks would be a breakthrough in
our understanding of the strong interaction and is therefore in the focus of
various high-energy heavy-ion research programs. The Compressed Baryonic Matter
(CBM) experiment at FAIR will play a unique role in the exploration of the QCD
phase diagram in the region of high net-baryon densities, because it is
designed to run at unprecedented interaction rates. High-rate operation is the
key prerequisite for high-precision measurements of multi-differential
observables and of rare diagnostic probes which are sensitive to the dense
phase of the nuclear fireball. The goal of the CBM experiment at SIS100
(sqrt(s_NN) = 2.7 - 4.9 GeV) is to discover fundamental properties of QCD
matter: the phase structure at large baryon-chemical potentials (mu_B > 500
MeV), effects of chiral symmetry, and the equation-of-state at high density as
it is expected to occur in the core of neutron stars. In this article, we
review the motivation for and the physics programme of CBM, including
activities before the start of data taking in 2022, in the context of the
worldwide efforts to explore high-density QCD matter.Comment: 15 pages, 11 figures. Published in European Physical Journal
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