14,024 research outputs found
Nuclear suppression of meson yields with large at the RHIC and the LHC
We calculate meson transverse momentum spectra in p+p collisions as
well as their nuclear suppressions in central A+A collisions both at the RHIC
and the LHC in LO and NLO with the QCD-improved parton model. We have included
the parton energy loss effect in hot/dense QCD medium with the effectively
medium-modified fragmentation functions in the higher-twist approach of
jet quenching. The nuclear modification factors of meson in central
Au+Au collisions at the RHIC and central Pb+Pb collisions at the LHC are
provided, and a nice agreement of our numerical results at NLO with the ALICE
measurement is observed. Predictions of yield ratios of neutral mesons such as
, and at large in relativistic
heavy-ion collisions are also presented for the first time.Comment: 7 pages, 8 figure
Stacking tunable interlayer magnetism in bilayer CrI3
Diverse interlayer tunability of physical properties of two-dimensional
layers mostly lies in the covalent-like quasi-bonding that is significant in
electronic structures but rather weak for energetics. Such characteristics
result in various stacking orders that are energetically comparable but may
significantly differ in terms of electronic structures, e.g. magnetism.
Inspired by several recent experiments showing interlayer
anti-ferromagnetically coupled CrI3 bilayers, we carried out first-principles
calculations for CrI3 bilayers. We found that the anti-ferromagnetic coupling
results from a new stacking order with the C2/m space group symmetry, rather
than the graphene-like one with R3 as previously believed. Moreover, we
demonstrated that the intra- and inter-layer couplings in CrI3 bilayer are
governed by two different mechanisms, namely ferromagnetic super-exchange and
direct-exchange interactions, which are largely decoupled because of their
significant difference in strength at the strong- and weak-interaction limits.
This allows the much weaker interlayer magnetic coupling to be more feasibly
tuned by stacking orders solely. Given the fact that interlayer magnetic
properties can be altered by changing crystal structure with different stacking
orders, our work opens a new paradigm for tuning interlayer magnetic properties
with the freedom of stacking order in two dimensional layered materials
Warped Brane worlds in Critical Gravity
We investigate the brane models in arbitrary dimensional critical gravity
presented in [Phys. Rev. Lett. 106, 181302 (2011)]. For the model of the thin
branes with codimension one, the Gibbons-Hawking surface term and the junction
conditions are derived, with which the analytical solutions for the flat, AdS,
and dS branes are obtained at the critical point of the critical gravity. It is
found that all these branes are embedded in an AdS spacetime, but, in
general, the effective cosmological constant of the AdS
spacetime is not equal to the naked one in the critical gravity,
which can be positive, zero, and negative. Another interesting result is that
the brane tension can also be positive, zero, or negative, depending on the
symmetry of the thin brane and the values of the parameters of the theory,
which is very different from the case in general relativity. It is shown that
the mass hierarchy problem can be solved in the braneworld model in the
higher-derivative critical gravity. We also study the thick brane model and
find analytical and numerical solutions of the flat, AdS, and dS branes. It is
find that some branes will have inner structure when some parameters of the
theory are larger than their critical values, which may result in resonant KK
modes for some bulk matter fields. The flat branes with positive energy density
and AdS branes with negative energy density are embedded in an -dimensional
AdS spacetime, while the dS branes with positive energy density are embedded in
an -dimensional Minkowski one.Comment: 14 pages, 7 figures, updated version, accepted by EPJ
DxFormer: A Decoupled Automatic Diagnostic System Based on Decoder-Encoder Transformer with Dense Symptom Representations
Diagnosis-oriented dialogue system queries the patient's health condition and
makes predictions about possible diseases through continuous interaction with
the patient. A few studies use reinforcement learning (RL) to learn the optimal
policy from the joint action space of symptoms and diseases. However, existing
RL (or Non-RL) methods cannot achieve sufficiently good prediction accuracy,
still far from its upper limit. To address the problem, we propose a decoupled
automatic diagnostic framework DxFormer, which divides the diagnosis process
into two steps: symptom inquiry and disease diagnosis, where the transition
from symptom inquiry to disease diagnosis is explicitly determined by the
stopping criteria. In DxFormer, we treat each symptom as a token, and formalize
the symptom inquiry and disease diagnosis to a language generation model and a
sequence classification model respectively. We use the inverted version of
Transformer, i.e., the decoder-encoder structure, to learn the representation
of symptoms by jointly optimizing the reinforce reward and cross entropy loss.
Extensive experiments on three public real-world datasets prove that our
proposed model can effectively learn doctors' clinical experience and achieve
the state-of-the-art results in terms of symptom recall and diagnostic
accuracy.Comment: 7 pages, 4 figures, 3 table
Effect of near-fault ground motions with long-period pulses on the tunnel
Investigations from recent strong earthquakes indicate most of the tunnels severely damaged are located near the causative faults. First, the dynamic response of the tunnel to the near-fault and far-field ground motions was investigated. The results show that the near-fault motions with long-period pulses especially the forward directivity pulses are more damaging than the typical far-field records, which should be reflected in the seismic design guideline for tunnels near causative faults. Furthermore, the effects of the key parameters for the simplified pulse on the dynamic response of the tunnel were also studied. Generally, the pulse with larger amplitude brings more energy and leads to larger strains in rock. Consequently, it becomes more damaging to the tunnel. The period of the pulse can remarkably influence the response of the tunnel. When the period of the pulse is less than 3.0 s, the pulse becomes less damaging to the tunnel with the increase of the period. Once the period exceeds 3.0 s, the pulse has little effect on the dynamic response of the tunnel. Thus, the earthquake with lower magnitude, which is likely to leads to lower period, may be more damaging to the tunnel. Besides, as the number of significant cycles increases, the damage potential of the ground motions increases accordingly. For the sake of security, two significant cycles in velocity-time history are recommended for the seismic design of tunnels close to ruptured faults
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