Zc(3900)Z_c(3900) as a DDˉ∗D\bar{D}^* molecule from the pole counting rule

A comprehensive study on the nature of the $Z_c(3900)$ resonant structure is carried out in this work. By constructing the pertinent effective Lagrangians and considering the important final-state-interaction effects, we first give a unified description to all the relevant experimental data available, including the $J/\psi\pi$ and $\pi\pi$ invariant mass distributions from the $e^+e^-\to J/\psi\pi\pi$ process, the $h_c\pi$ distribution from $e^+e^-\to h_c\pi\pi$ and also the $D\bar D^{*}$ spectrum in the $e^+e^-\to D\bar D^{*}\pi$ process. After fitting the unknown parameters to the previous data, we search the pole in the complex energy plane and find only one pole in the nearby energy region in different Riemann sheets. Therefore we conclude that $Z_c(3900)$ is of $D\bar D^*$ molecular nature, according to the pole counting rule method~[Nucl.~Phys.~A543, 632 (1992); Phys.~Rev.~D 35,~1633 (1987)]. We emphasize that the conclusion based upon the pole counting method is not trivial, since both the $D\bar D^{*}$ contact interactions and the explicit $Z_c$ exchanges are introduced in our analyses and they lead to the same conclusion.Comment: 21 pages, 9 figures. To match the published version in PRD. Additional discussion on the spectral density function is include

Risk assessment of oil price from static and dynamic modelling approaches

The price gap between West Texas Intermediate (WTI) and Brent crude oil markets has been completely changed in the past several years. The price of WTI was always a little larger than that of Brent for a long time. However, the price of WTI has been surpassed by that of Brent since 2011. The new market circumstances and volatility of oil price require a comprehensive re-estimation of risk. Therefore, this study aims to explore an integrated approach to assess the price risk in the two crude oil markets through the value at risk (VaR) model. The VaR is estimated by the extreme value theory (EVT) and GARCH model on the basis of generalized error distribution (GED). The results show that EVT is a powerful approach to capture the risk in the oil markets. On the contrary, the traditional variance–covariance (VC) and Monte Carlo (MC) approaches tend to overestimate risk when the confidence level is 95%, but underestimate risk at the confidence level of 99%. The VaR of WTI returns is larger than that of Brent returns at identical confidence levels. Moreover, the GED-GARCH model can estimate the downside dynamic VaR accurately for WTI and Brent oil returns

Measurement of Temperature Distribution Based on Optical Fiber-Sensing Technology and Tunable Diode Laser Absorption Spectroscopy

Temperature is an important physical quantity in most industrial processes. Distributed temperature sensor (DTS), fiber Bragg grating (FBG), and tunable diode laser absorption spectroscopy (TDLAS) are three primary techniques for temperature measurement using fiber optic sensing and spectrum technology. The DTS system can monitor space temperature field along the fiber in real time. In addition, it also can locate a fire source using two sections of optical fibers which are placed orthogonally to each other. The FBG temperature sensor is used to measure the point temperature. The temperature sensitivity of the bare FBG is 10.68 pm/°C and the linearity is 0.99954 in the range of 30–100°C. Based on tunable diode laser absorption spectroscopy (TDLAS), two-dimensional (2D) distribution reconstructions of gas temperature are realized using an algebraic reconstruction technique (ART). The results are in agreement with the simulation results, and the time resolution is less than 1 s

Grow and Merge: A Unified Framework for Continuous Categories Discovery

Although a number of studies are devoted to novel category discovery, most of them assume a static setting where both labeled and unlabeled data are given at once for finding new categories. In this work, we focus on the application scenarios where unlabeled data are continuously fed into the category discovery system. We refer to it as the {\bf Continuous Category Discovery} ({\bf CCD}) problem, which is significantly more challenging than the static setting. A common challenge faced by novel category discovery is that different sets of features are needed for classification and category discovery: class discriminative features are preferred for classification, while rich and diverse features are more suitable for new category mining. This challenge becomes more severe for dynamic setting as the system is asked to deliver good performance for known classes over time, and at the same time continuously discover new classes from unlabeled data. To address this challenge, we develop a framework of {\bf Grow and Merge} ({\bf GM}) that works by alternating between a growing phase and a merging phase: in the growing phase, it increases the diversity of features through a continuous self-supervised learning for effective category mining, and in the merging phase, it merges the grown model with a static one to ensure satisfying performance for known classes. Our extensive studies verify that the proposed GM framework is significantly more effective than the state-of-the-art approaches for continuous category discovery.Comment: This paper has already been accepted by 36th Conference on Neural Information Processing Systems (NeurIPS 2022

Diagnosis of pulmonary tuberculosis among asymptomatic HIV+ patients in Guangxi, China

BACKGROUND: Pulmonary tuberculosis (PTB) among asymptomatic Chinese patients with HIV infection has not been investigated despite high tuberculosis burden in China. This study was aimed to evaluate the prevalence, risk factors and clinical outcomes of PTB among asymptomatic patients with HIV/AIDS in Guangxi to facilitate the development of diagnostic and treatment strategies. METHODS: All asymptomatic adult HIV-infected patients with CD4 < 350 cells/µl who attended four HIV clinics in Guangxi between August 2006 and March 2008 were evaluated for active PTB with physical examination, chest X-ray (CXR), sputum smear and/or sputum liquid culture. Data were described using median (interquartile range, IQR) and frequencies. Univariate and multivariate Logistic regression analyses were performed to identify risk factors associated with PTB. RESULTS: Among 340 asymptomatic subjects, 15 (4%) were diagnosed with PTB, with 4 (27%) sputum smear positive and 8 (53%) sputum culture positive. CXR has higher diagnostic sensitivity (87%) than sputum smear (25%) and sputum culture (67%), but lower specificity (56%) compared with sputum smear (99%) and culture (100%). In univariate analysis, injection drug user, body mass index (BMI) < 18 kg/m(2), CD4 < 50 cells/µl and presence of peripheral lymphadenopathy were associated with an increased risk of asymptomatic PTB, while in multivariate analysis only peripheral lymphadenopathy maintained statistical significance (OR = 7.6, 95%CI 1.4 - 40). Patients with negative smear and minor or no abnormalities on CXR had longer interval between screening and TB treatment. CONCLUSIONS: PTB was relatively common in this group of HIV(+) asymptomatic Chinese patients. Diagnosis is challenging especially where sputum culture is unavailable. These findings suggest that an enhanced evaluation for PTB needs to be integrated with HIV care in China and transmission prevention in China to control at both households and health care facilities, especially for patients with factors associated with a higher risk of PTB

Poly[[μ2-aqua-μ3-(4-carb­oxy-2-propyl-1H-imidazole-5-carboxyl­ato-κ4 N 3,O 4:O 4:O 5)-sodium] hemihydrate]

In the title compound, {[Na(C8H9N2O4)(H2O)]·0.5H2O}n, the Na+ ion is coordinated by two bridging water mol­ecules, one N atom and three O atoms from three 4-carb­oxy-2-propyl-1H-imidazole-5-carboxyl­ate (H2pimdc) ligands. Adjacent Na+ ions are linked alternately by two water O atoms and two carb­oxy O atoms into a chain along [001]. These chains are connected through the coordination of the carboxyl­ate O atoms to the Na+ ions, forming a three-dimensional structure. An intra­molecular O—H⋯O hydrogen bond and inter­molecular N—H⋯O and O—H⋯O hydrogen bonds are present in the crystal structure