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Search Results: 1 - 10 of 26599 matches for " Xue Ling "
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Edge Colorings of Planar Graphs without 6-Cycles with Two Chords  [PDF]
Ling Xue, Jianliang Wu
Open Journal of Discrete Mathematics (OJDM) , 2013, DOI: 10.4236/ojdm.2013.32016
Abstract:

It is proved here that if a planar graph has maximum degree at least 6 and any 6-cycle contains at most one chord, then it is of class 1.

Optimization of Dry Ashing of Whole Blood Samples for Trace Metal Analysis  [PDF]
Stefanie A. Bragg, Zi-Ling Xue
American Journal of Analytical Chemistry (AJAC) , 2011, DOI: 10.4236/ajac.2011.28114
Abstract: Dry ashing is an established method. Ashing whole blood samples are, however, often difficult to carry out with significant sample loss, and the procedure is not well documented. A new procedure has been devel- oped and optimized to dry-ash whole blood samples for trace metal analyses. The procedure reduces both the dry-ashing time by more than two thirds and sample loss. The ashed sample can be readily used in subse- quent, simultaneous or individual analysis of several metals by ICP-OES, as demonstrated in the analysis of a whole blood sample. The new procedure is simple, inexpensive, and faster than the established method.
The Study on Community Health Education of Empty Nest Elderly  [PDF]
Ling Gao, Xue Cao, Min Zhang
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.510B028
Abstract:

Objective:To study the demands of community health education on the empty nest elderly and analyse the related factors. Methods:The 36-Item Short-Form Health Survey(SF-36), activities of daily living (ADL) and the community health services satisfaction scale were used to investigate the community health service demand and supply of 358 empty nesters. Results:The results showed that the ability of self-care was worse and needed more nursing or caring from others in the empty nest elderly; the empty nest elderly, in comparison with the non-empty-nest elderly, had lower physical and mental scores. With the age changing, the requirements of community health services were different in empty nest elderly and the satisfaction of community health service was low in the empty nest (39.1%). Conclusions: Empty nest elderly generally needed the different degree of community health education demands. The utilization rates of community health education were low.

The network level reproduction number for infectious diseases with both vertical and horizontal transmission
Ling Xue,Caterina Scoglio
Quantitative Biology , 2012, DOI: 10.1016/j.mbs.2013.02.004
Abstract: A wide range of infectious diseases are both vertically and horizontally transmitted. Such diseases are spatially transmitted via multiple species in heterogeneous environments, typically described by complex meta-population models. The reproduction number is a critical metric predicting whether the disease can invade the meta-population system. This paper presents the reproduction number for a generic disease vertically and horizontally transmitted among multiple species in heterogeneous networks, where nodes are locations, and links reflect outgoing or incoming movement flows. The metapopulation model for vertically and horizontally transmitted diseases is gradually formulated from two species, two-node network models. We derived an explicit expression of the reproduction number, which is the spectral radius of a matrix reduced in size with respect to the original next generation matrix. The reproduction number is shown to be a function of vertical and horizontal transmission parameters, and the lower bound is the reproduction number for horizontal transmission. As an application, the reproduction number and its bounds for the Rift Valley fever zoonosis, where livestock, mosquitoes, and humans are the involved species are derived. By computing the reproduction number for different scenarios through numerical simulations, we found the reproduction number is affected by livestock movement rates only when parameters are heterogeneous across nodes. To summarize, our study contributes the reproduction number for vertically and horizontally transmitted diseases in heterogeneous networks. This explicit expression is easily adaptable to specific infectious diseases, affording insights into disease evolution.
The network-level reproduction number and extinction threshold for vector-borne diseases
Ling Xue,Caterina Scoglio
Quantitative Biology , 2013,
Abstract: The reproduction number of deterministic models is an essential quantity to predict whether an epidemic will spread or die out. Thresholds for disease extinction contribute crucial knowledge on disease control, elimination, and mitigation of infectious diseases. Relationships between the basic reproduction numbers of two network-based ordinary differential equation vector-host models, and extinction thresholds of corresponding continuous-time Markov chain models are derived under some assumptions. Numerical simulation results for malaria and Rift Valley fever transmission on heterogeneous networks are in agreement with analytical results without any assumptions, reinforcing the relationships may always exist and proposing a mathematical problem of proving their existences in general. Moreover, numerical simulations show that the reproduction number is not monotonically increasing or decreasing with the extinction threshold. Key parameters in predicting uncertainty of extinction thresholds are identified using Latin Hypercube Sampling/Partial Rank Correlation Coefficient. Consistent trends of extinction probability observed through numerical simulations provide novel insights into mitigation strategies to increase the disease extinction probability. Research findings may improve understandings of thresholds for disease persistence in order to control vector-borne diseases.
B?cklund-Darboux Transformations and Discretizations of Super KdV Equation
Ling-Ling Xue,Qing Ping Liu
Physics , 2013, DOI: 10.3842/SIGMA.2014.045
Abstract: For a generalized super KdV equation, three Darboux transformations and the corresponding B\"acklund transformations are constructed. The compatibility of these Darboux transformations leads to three discrete systems and their Lax representations. The reduction of one of the B\"acklund-Darboux transformations and the corresponding discrete system are considered for Kupershmidt's super KdV equation. When all the odd variables vanish, a nonlinear superposition formula is obtained for Levi's B\"acklund transformation for the KdV equation.
Theoretical study of small Mo clusters and molecular nitrogen adsorption on Mo clusters

Lei Xue-Ling,

中国物理 B , 2010,
Abstract: This paper studies the small molybdenum clusters of Mon (n=2--8) and their adsorption of N2 molecule by using the density functional theory (DFT) with the generalized gradient approximation. The optimized structures of Mon clusters show the onset of a structural transition from a close-packed structure towards a body-centred cubic structure occurred at n=7. An analysis of adsorption energies suggests that the Mo2 is of high inertness and Mo6 cluster is of high activity against the adsorption of N2. Calculated results indicate that the N2 molecule prefers end-on mode by forming a linear or quasi-linear structure Mo--N--N, and the adsorption of nitrogen on molybdenum clusters is molecular adsorption with slightly elongated N--N bond. The electron density of highest occupied molecular orbital and lowest unoccupied molecular orbital, and the partial density of states of representative cluster are also used to characterize the adsorption properties of N2 on the sized Mon clusters.
Supersymmetric KdV equation: Darboux transformation and discrete systems
Ling-Ling Xue,D. Levi,Q. P. Liu
Physics , 2013, DOI: 10.1088/1751-8113/46/50/502001
Abstract: For the supersymmetric KdV equation, a proper Darboux transformation is presented. This Darboux transformation leads to the B\"{a}cklund transformation found early by Liu and Xie \cite{liu2}. The Darboux transformation and the related B\"{a}cklund transformation are used to construct integrable super differential-difference and difference-difference systems. The continuum limits of these discrete systems and of their Lax pairs are also considered.
Heart pacemaker wear life model based on frequent properties and life distribution  [PDF]
Qiao-Ling Tong, Xue-Cheng Zou, Jin Tang, Heng-Qing Tong
Journal of Biomedical Science and Engineering (JBiSE) , 2010, DOI: 10.4236/jbise.2010.34052
Abstract: The lifetime of heart pacemaker is important for patient and researcher. To forecast the lifetime of heart pacemakers we must determine its distribution regularity. In this paper, a heart pacemaker wear life model is introduced by using frequency property, and a life distribution is presented. The parametric properties of the density are studied. The moment estimator with negative order is used, which is just the maximum likelihood estimator. A new method of parameter estimate, F estimate of parameter, is proposed. This method is suitable to both truncated samples and complete samples, whether or not the distribution can be transformed into a standard distribution without any parameters.
Investigation of Patch Antenna Based on Photonic Band-Gap Substrate with Heterostructures
Zhenghua Li,Yan Ling Xue,Tinggen Shen
Mathematical Problems in Engineering , 2012, DOI: 10.1155/2012/151603
Abstract: The characteristics of the patch antenna based on photonic band-gap (PBG) substrate with heterostructures were studied numerically by using the method of finite difference time domain (FDTD). The results indicate that, comparing to the conventional patch antennas, the expansion of working frequency band of the new patch antenna can be realized and its radiation efficiency also can be improved notably with the influence of PBG. In addition, for this new kind of patch antenna, its return loss is much less and there are two minimum values for return loss corresponding to the resonant frequency of the two different photonic crystals made of the substrate. Its physical mechanism lies on the PBG which suppresses the surface waves propagating along the surface of the substrate and reflects most of electromagnetic wave energy radiated to the substrate significantly.
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