1,960 research outputs found
Phase diagram of QCD at finite temperature and chemical potential from lattice simulations with dynamical Wilson quarks
We present the first results for lattice QCD at finite temperature and
chemical potential with four flavors of Wilson quarks. The calculations
are performed using the imaginary chemical potential method at ,
0.001, 0.15, 0.165, 0.17 and 0.25, where is the hopping parameter,
related to the bare quark mass and lattice spacing by
. Such a method allows us to do large scale Monte Carlo
simulations at imaginary chemical potential . By analytic
continuation of the data with to real values of the chemical
potential, we expect at each , a transition line
on the plane, in a region relevant to the search for quark gluon
plasma in heavy-ion collision experiments. The transition is first order at
small or large quark mass, and becomes a crossover at intermediate quark mass.Comment: Published versio
Phase structure of lattice QCD with two flavors of Wilson quarks at finite temperature and chemical potential
We present results for phase structure of lattice QCD with two degenerate
flavors () of Wilson quarks at finite temperature and small baryon
chemical potential . Using the imaginary chemical potential for which
the fermion determinant is positive, we perform simulations at points where the
ratios of pseudo-scalar meson mass to the vector meson mass are
between and as well as in the quenched limit. By analytic
continuation to real quark chemical potential , we obtain the transition
temperature as a function of small . We attempt to determine the nature
of transition at imaginary chemical potential by histogram, MC history, and
finite size scaling. In the infinite heavy quark limit, the transition is of
first order. At intermediate values of quark mass corresponding to the
ratio of in the range from to at
, the MC simulations show absence of phase transition.Comment: 10 pages, 17 figures;16 figures;9 pages,10 figures;10 pages,11
figure
Anisotropic Electron-Hole Excitation and Large Linear Dichroism in Two-Dimensional Ferromagnet CrSBr with In-Plane Magnetization
The observation of magnetic ordering in atomically thin CrI and
CrGeTe monolayers has aroused intense interest in condensed matter
physics and material science. Studies of van de Waals two-dimensional (2D)
magnetic materials are of both fundamental importance and application interest.
In particular, exciton-enhanced magneto-optical properties revealed in CrI
and CrBr monolayers have expanded the understanding of exciton physics in
2D materials. Unlike CrI and CrBr with out-of-plane magnetization,
CrSBr has an in-plane magnetic moment, therefore, providing a good opportunity
to study the magnetic linear dichroism and high-order magneto-optical effects.
Here, based on the many-body perturbation method within density-functional
theory, we have studied quasiparticle electronic structure, exciton, and
optical properties in CrSBr monolayer. Strongly bounded exciton has been
identified with the first bright exciton located at 1.35 eV, in good agreement
with an experiment of photoluminescence (Nat. Mater. \textbf{20}, 1657 (2021)).
Strong contrast in the optical absorption is found between the electric fields
lying along the in-plane two orthogonal directions. In accordance with a
typical and realistic experimental setup, we show that the rotation angle of
linear polarized light, either reflected or transmitted, could be comparable
with those revealed in black phosphorene. Such large linear dichroism arises
mainly from anisotropic in-plane crystal structure. The magnetic contribution
from the off-diagonal component of dielectric function to the linear dichroism
in CrSBr is negligible. Our findings not only have revealed excitonic effect on
the optical and magneto-optical properties in 2D ferromagnet CrSBr, but also
have shown its potential applications in 2D optics and optoelectronics.Comment: 47 pages, 24 figure
QCD at Finite temperature and density with staggered and Wilson quarks
One of the most challenging issues in particle physics is to study QCD in
extreme conditions. Precise determination of the QCD phase diagram on
temperature and chemical potential plane will provide valuable
information for quark-gluon plasma (QGP) and neutron star physics. We present
results for phase structure on the plane for lattice QCD with Wilson
fermions from strong coupling Hamiltonian analysis and Kogut-Susskind Fermions
from Lagrangian Monte Carlo simulations at intermediate coupling.Comment: Lattice 2004 (nonzero
Computational Experiment Study on Selection Mechanism of Project Delivery Method Based on Complex Factors
Project delivery planning is a key stage used by the project owner (or project investor) for organizing design, construction, and other operations in a construction project. The main task in this stage is to select an appropriate project delivery method. In order to analyze different factors affecting the PDM selection, this paper establishes a multiagent model mainly to show how project complexity, governance strength, and market environment affect the project owner’s decision on PDM. Experiment results show that project owner usually choose Design-Build method when the project is very complex within a certain range. Besides, this paper points out that Design-Build method will be the prior choice when the potential contractors develop quickly. This paper provides the owners with methods and suggestions in terms of showing how the factors affect PDM selection, and it may improve the project performance
Diagnostic value of two dimensional shear wave elastography combined with texture analysis in early liver fibrosis.
BACKGROUND: Staging diagnosis of liver fibrosis is a prerequisite for timely diagnosis and therapy in patients with chronic hepatitis B. In recent years, ultrasound elastography has become an important method for clinical noninvasive assessment of liver fibrosis stage, but its diagnostic value for early liver fibrosis still needs to be further improved. In this study, the texture analysis was carried out on the basis of two dimensional shear wave elastography (2D-SWE), and the feasibility of 2D-SWE plus texture analysis in the diagnosis of early liver fibrosis was discussed.
AIM: To assess the diagnostic value of 2D-SWE combined with textural analysis in liver fibrosis staging.
METHODS: This study recruited 46 patients with chronic hepatitis B. Patients underwent 2D-SWE and texture analysis; Young\u27s modulus values and textural patterns were obtained, respectively. Textural pattern was analyzed with regard to contrast, correlation, angular second moment (ASM), and homogeneity. Pathological results of biopsy specimens were the gold standard; comparison and assessment of the diagnosis efficiency were conducted for 2D-SWE, texture analysis and their combination.
RESULTS: 2D-SWE displayed diagnosis efficiency in early fibrosis, significant fibrosis, severe fibrosis, and early cirrhosis (AUC \u3e 0.7, P \u3c 0.05) with respective AUC values of 0.823 (0.678-0.921), 0.808 (0.662-0.911), 0.920 (0.798-0.980), and 0.855 (0.716-0.943). Contrast and homogeneity displayed independent diagnosis efficiency in liver fibrosis stage (AUC \u3e 0.7, P \u3c 0.05), whereas correlation and ASM showed limited values. AUC of contrast and homogeneity were respectively 0.906 (0.779-0.973), 0.835 (0.693-0.930), 0.807 (0.660-0.910) and 0.925 (0.805-0.983), 0.789 (0.639-0.897), 0.736 (0.582-0.858), 0.705 (0.549-0.883) and 0.798 (0.650-0.904) in four liver fibrosis stages, which exhibited equivalence to 2D-SWE in diagnostic efficiency (P \u3e 0.05). Combined diagnosis (PRE) displayed diagnostic efficiency (AUC \u3e 0.7, P \u3c 0.01) for all fibrosis stages with respective AUC of 0.952 (0.841-0.994), 0.896 (0.766-0.967), 0.978 (0.881-0.999), 0.947 (0.835-0.992). The combined diagnosis showed higher diagnosis efficiency over 2D-SWE in early liver fibrosis (P \u3c 0.05), whereas no significant differences were observed in other comparisons (P \u3e 0.05).
CONCLUSION: Texture analysis was capable of diagnosing liver fibrosis stage, combined diagnosis had obvious advantages in early liver fibrosis, liver fibrosis stage might be related to the hepatic tissue hardness distribution
Short-Term Coalmine Gas Concentration Prediction Based on Wavelet Transform and Extreme Learning Machine
It is well known that coalmine gas concentration forecasting is very significant to ensure the safety of mining. Owing to the high-frequency, nonstationary fluctuations and chaotic properties of the gas concentration time series, a gas concentration forecasting model utilizing the original raw data often leads to an inability to provide satisfying forecast results. A hybrid forecasting model that integrates wavelet transform and extreme learning machine (ELM) termed as WELM (wavelet based ELM) for coalmine gas concentration is proposed. Firstly, the proposed model employs Mallat algorithm to decompose and reconstruct the gas concentration time series to isolate the low-frequency and high-frequency information. Then, ELM model is built for the prediction of each component. At last, these predicted values are superimposed to obtain the predicted values of the original sequence. This method makes an effective separation of the feature information of gas concentration time series and takes full advantage of multi-ELM prediction models with different parameters to achieve divide and rule. Comparative studies with existing prediction models indicate that the proposed model is very promising and can be implemented in one-step or multistep ahead prediction
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