NDND and NBNB systems in quark delocalization color screening model

The $ND$ and $NB$ systems with $I=0$ and $1$, $J^{P}=\frac{1}{2}^{\pm}$, $\frac{3}{2}^{\pm}$, and $\frac{5}{2}^{\pm}$ are investigated within the framework of quark delocalization color screening model. The results show that all the positive parity states are unbound. By coupling to the $ND^{*}$ channel, the state $ND$ with $I=0,~J^{P}=\frac{1}{2}^{-}$ can form a bound state, which can be invoked to explain the observed $\Sigma(2800)$ state. The mass of the $ND^{*}$ with $I=0,~J^{P}=\frac{3}{2}^{-}$ is close to that of the reported $\Lambda_{c}(2940)^{+}$, which indicates that $\Lambda_{c}(2940)^{+}$ can be explained as a $ND^{*}$ molecular state in QDCSM. Besides, the $\Delta D^{*}$ with $I=1,~J^{P}=\frac{5}{2}^{-}$ is also a possible resonance state. The results of the bottom case of $NB$ system are similar to those of the $ND$ system. Searching for these states will be a challenging subject of experiments.Comment: 7 pages, 3 figures. arXiv admin note: text overlap with arXiv:1510.04648, arXiv:1311.473

Examining Contributors to Preschoolers’ Classroom Engagement using Structural Equation Modeling

The purpose of this study is to demonstrate whether and how teacher-child interactions, teacher-child relationships, children’s self-control, parents’ education levels, teachers’ teaching experience and education levels, and classroom physical environment impact children’s engagement levels. Preschoolers from Head Start programs and a university childcare center (N = 135, M = 54.93 months, SD = 7.50) and 15 preschool classroom teachers in East Tennessee participated in the study. Classroom head teachers rated child’s engagement, teacher-child interaction, teacher-child relationships, and children’s self-control using provided questionnaires. The primary researcher assessed the classroom physical environment and determined the reliability for the Children’s Physical Environments Rating Scale (CPERS). The structural equation modeling (SEM) statistical approach was employed to analyze the data. The results showed that the level of preschoolers’ engagement in classroom learning activities was directly associated with their self-control (β = .37, p \u3c .001). Preschoolers’ engagement was not indirectly associated with children’s self-control through teacher-child interaction. The level of engagement of preschoolers in classroom learning activities did not directly associate with teacher-child relationships but was indirectly associated with the teacher-child relationship through children’s self-control (β = .20 , p \u3c .001 ). When separating the two subscales of teacher-child relationship (closeness and conflict), teacher-child closeness was directly associated with children’s engagement level (β = .22, p = .003). In addition, teacher-child conflict was both directly (β = - .17, p = .022) and indirectly associated with child’s engagement level through children’s self-control (β = .26, p \u3c .001). Classroom physical environment did not directly predict the level of engagement of preschoolers, while indirect relationships were found between the classroom physical environment scores and the level of engagement of preschoolers, and the relationship was mediated by children’s self-control (β = .09, p = .050). The study offers implications for teachers as they work on enhancing children’s engagement level in their learning activities. Future research suggested by this study include further exploration of intervention strategies to increase children’s active engagement. Increasing sample size and obtaining reliability of the measures on children’s behaviors would also improve the rigor of the study

Research on Green Express Packaging in the Era of Online Shopping

With the rapid development of electronic commerce in China, the rapid increase in the number of express packages has brought about great environmental problems while bringing great convenience to us. Based on the concept of green logistics, this paper discusses the problems of unreasonable express packaging materials, excessive packaging and the absence of packaging waste recovery system from both theoretical and practical aspects, and puts forward the countermeasures to promote the green express packaging in the era of online shopping. This paper aims to find the ways, measures and methods to solve the problems of express packaging, so as to realize the load reduction and greening of express packaging in China

Trellis-Coded Modulation in PSK and DPSK Communications

Coded modulation is for the first time investigated in phase-modulated systems, with coherent as well as differential detection. We find coding gains of 3.0 and 1.7 dB, already with the simplest possible trellis code

Unequal bit error probability in coherent QPSK fiber-optic systems using phase modulator based transmitters

We report on the occurrence of unequal bit error probability in a coherent quadrature phase shift keying (QPSK) fiber optic system. The bit error rates (BER) of two QPSK bits are derived individually based on the developed system model, and they turn out to differ by more than an order of magnitude for a phase modulator based transmitter. The phenomenon, previously unreported, arises because such a transmitter introduces a controlled form of inter-symbol-interference (ISI), and the receiver low-pass filters affect this ISI differently for the two bits. The optimum bandwidth of the receiver low-pass filter is obtained from the analytic derivation, which is about 0.7 times the symbol rate. We propose two simple system modifications, one in the transmitter and one in the receiver, to compensate for the phenomenon and equalize the two BER\u27s. Those modifications improve the system performance by about 2~dB without adding any extra hardware

Unequal bit error probability in coherent QPSK fiber-optic systems using phase modulator based transmitters

We report on the occurrence of unequal bit error probability in a coherent quadrature phase shift keying (QPSK) fiber optic system. The bit error rates (BER) of two QPSK bits are derived individually based on the developed system model, and they turn out to differ by more than an order of magnitude for a phase modulator based transmitter. The phenomenon, previously unreported, arises because such a transmitter introduces a controlled form of inter-symbol-interference (ISI), and the receiver low-pass filters affect this ISI differently for the two bits. The optimum bandwidth of the receiver low-pass filter is obtained from the analytic derivation, which is about 0.7 times the symbol rate. We propose two simple system modifications, one in the transmitter and one in the receiver, to compensate for the phenomenon and equalize the two BER\u27s. Those modifications improve the system performance by about 2~dB without adding any extra hardware

Transmitter comparison and unequal bit error probabilities in coherent QPSK systems

We compare different QPSK transmitters and find that some simple configurations can give rise to a significant difference in BER between the two transmitted bits. The optimum receiver filter bandwidth is affected by this phenomenon. \ua9 2006 Optical Society of America

Direct sampling method to inverse wave-number-dependent source problems (part I): determination of the support of a stationary source

This paper is concerned with a direct sampling method for imaging the support of a frequency-dependent source term embedded in a homogeneous and isotropic medium. The source term is given by the Fourier transform of a time-dependent source whose radiating period in the time domain is known. The time-dependent source is supposed to be stationary in the sense that its compact support does not vary along the time variable. Via a multi-frequency direct sampling method, we show that the smallest strip containing the source support and perpendicular to the observation direction can be recovered from far-field patterns at a fixed observation angle. With multiple but sparse observation directions, the shape of the convex hull of the source support can be recovered. The frequency-domain analysis performed here can be used to handle inverse time-dependent source problems. Our algorithm has low computational overhead and is robust against noise. Numerical experiments in both two and three dimensions have proved our theoretical findings

Antimicrobial Resistance in <em>Salmonella</em>: Its Mechanisms in Comparison to Other Microbes, and The Reversal Effects of Traditional Chinese Medicine on Its Resistance

Salmonella is one of the most notable pathogens leading to the outbreak of foodborne diseases worldwide. Antimicrobial chemotherapy with 3rd-generation cephalosporins or fluoroquinolones is often used for severe infections caused by Salmonella. Therefore, antibiotic or antimicrobial resistance (AMR) of Salmonella is a serious threat to human and animal health in China and worldwide. In order to better understand the current situation and development status of AMR in Salmonella isolates, this chapter will provide an overview of the following: 1. The history and development trend of AMR in Salmonella, and a comparison of its AMR with that of other major pathogenic bacteria in animals. 2. The AMR mechanisms of Salmonella to various antibiotics, with a particular focus on the commonly used antibiotics. 3. The mechanisms of the spread of AMR in Salmonella, including the AMR genes or mobile genetic elements carrying AMR genes among microbes, and among people, animal-derived foods, and the environment. 4. The elimination or reversal of AMR in Salmonella by using traditional Chinese medicine or the active ingredients in traditional Chinese medicine. 5. The development of detection technology for Salmonella serotypes, virulence, and AMR, and the improvement from conventional detection methods to more advanced biological detection methods and bioinformatics technology