The Method of Approximate Particular Solutions for Solving Elliptic Problems with Variable Coefficients

A new version of the method of approximate particular solutions (MAPSs) using radial basis functions (RBFs) has been proposed for solving a general class of elliptic partial differential equations. In the solution process, the Laplacian is kept on the left-hand side as a main differential operator. The other terms are moved to the right-hand side and treated as part of the forcing term. In this way, the close-form particular solution is easy to obtain using various RBFs. The numerical scheme of the new MAPSs is simple to implement and yet very accurate. Three numerical examples are given and the results are compared to Kansa\u27s method and the method of fundamental solutions

Optimization of multi-model ensemble forecasting of typhoon waves

Accurately forecasting ocean waves during typhoon events is extremely important in aiding the mitigation and minimization of their potential damage to the coastal infrastructure, and the protection of coastal communities. However, due to the complex hydrological and meteorological interaction and uncertainties arising from different modeling systems, quantifying the uncertainties and improving the forecasting accuracy of modeled typhoon-induced waves remain challenging. This paper presents a practical approach to optimizing model-ensemble wave heights in an attempt to improve the accuracy of real-time typhoon wave forecasting. A locally weighted learning algorithm is used to obtain the weights for the wave heights computed by the WAVEWATCH III wave model driven by winds from four different weather models (model-ensembles). The optimized weights are subsequently used to calculate the resulting wave heights from the model-ensembles. The results show that the optimization is capable of capturing the different behavioral effects of the different weather models on wave generation. Comparison with the measurements at the selected wave buoy locations shows that the optimized weights, obtained through a training process, can significantly improve the accuracy of the forecasted wave heights over the standard mean values, particularly for typhoon-induced peak waves. The results also indicate that the algorithm is easy to implement and practical for real-time wave forecasting

METHOD OF FUNDAMENTAL SOLUTIONS WITH EXTERNAL SOURCE FOR THE EIGENFREQUENCIES OF WAVEGUIDES

ABSTRACT This study adopts a meshless numerical method, the combination of the method of fundamental solutions (MFS) and method of particular solutions (MPS) following the lead of Reutskiy, to determine the eigenfrequencies of four different waveguides, based on the principle of physical response of a system exposed to external source. The response amplitudes to determine the resonant frequencies for the eigenproblems are used. We use the MFS with external source (MFS-ES) and MPS to solve a sequence of inhomogeneous problems for the determination of the eigenfrequencies. This is an alternative to the typical methods of directly solving the homogeneous matrix system to search for the eigenvalues in an eigenproblem. The square, elliptic, concentric annular and eccentric annular waveguides are analyzed to demonstrate the capability and robustness of the present meshless numerical method. In the numerical experiments, the computational results are not sensitive at all to the locations of the external source. Furthermore, the spurious eigenfrequencies will not occur in this boundary-type meshless method which is different from other numerical methods

A New Business Model of Electronic Commerce with Innovative Strategies

There are a lot of problems that make the business of electronic stores very difficult, especially for those firms that lack the required expertise and resources for running an electronic business. This study proposes a new business model of electronic commerce (EC), which aims to tackle those problems and help enterprises run electronic stores well. This model applies the franchise system of chain store, a very successful modern business model, to the management of electronic stores to take advantage of the chain’s competitive power by integrating individual affiliate sites as a whole. There are eight components in the model. Implementation strategies of the model, which are quite different from those generic strategies commonly used in implementing business models, are also proposed. The feasibility of the model and its implementation strategies were validated using the Nominal Group Technique (NGT), the case study, and the questionnaire survey approaches. Finally, practical implications for applying the model are discussed, and directions for further study are also suggested

A Shallow Ritz Method for Elliptic Problems with Singular Sources

In this paper, a shallow Ritz-type neural network for solving elliptic equations with delta function singular sources on an interface is developed. There are three novel features in the present work; namely, (i) the delta function singularity is naturally removed, (ii) level set function is introduced as a feature input, (iii) it is completely shallow, comprising only one hidden layer. We first introduce the energy functional of the problem and then transform the contribution of singular sources to a regular surface integral along the interface. In such a way, the delta function singularity can be naturally removed without introducing a discrete one that is commonly used in traditional regularization methods, such as the well-known immersed boundary method. The original problem is then reformulated as a minimization problem. We propose a shallow Ritz-type neural network with one hidden layer to approximate the global minimizer of the energy functional. As a result, the network is trained by minimizing the loss function that is a discrete version of the energy. In addition, we include the level set function of the interface as a feature input of the network and find that it significantly improves the training efficiency and accuracy. We perform a series of numerical tests to show the accuracy of the present method and its capability for problems in irregular domains and higher dimensions

Impact of interleukin-28B polymorphism on HCV-1 infected patients treated with response-guided therapy

SummaryBackgroundSingle nucleotide polymorphisms (SNPs) of interleukin-28B (IL28B) were associated with sustained virological response (SVR) in hepatitis C virus genotype 1 (HCV-1) infected patients treated with a standard 48-week regimen of peginterferon and ribavirin combination. Whether IL28B SNP genotype would be the influential prognosticator for patients treated with response-guided therapy (RGT) is still not well understood.AimsTo investigate the impact of IL28B rs809917 genotype on HCV-1 infected patients treated with RGT.MethodsA total of 128 consecutive treatment-naïve HCV-1 infected patients between July 2006 and July 2011 were analyzed. For rapid virological response (RVR) patients, we allowed an abbreviated 24-week regimen regardless of baseline viral loads; otherwise, a 48-week regimen was implemented (for patients with early virological response). The IL28B rs8099917 SNP genotypes were determined accordingly.ResultsA total of 117 patients (91.4%) were of rs8099917 TT genotype and 11 (8.6%) were of GT/GG genotype. Eighty-two of the 128 (64.1%) patients achieved SVR, occurring in 54 of 67 RVR patients (80.6%) and 28 of 61 non-RVR patients (45.9%, p < 0.001). Compared to the GT/GG genotype, patients with the TT genotype had significantly higher SVR rates (67.5% vs. 27.3%; p = 0.008) and low relapse rates (28.2% vs. 70.0%; p = 0.006). The multivariate analysis showed that RVR (odds ratio, 4.51; 95% confidence interval, 1.87–10.90; p = 0.001) and rs8099917 TT genotype (odds ratio, 6.91; 95% confidence interval, 1.53–31.17; p = 0.012) were independent factors associated with SVR.ConclusionFor HCV-1 infected patients who were treated with RGT, the IL28B unfavorable genotype predicted a higher relapse rate; RVR and IL28B favorable genotype were independent factors associated with SVR in patients treated with RGT

Changes in endotracheal tube cuff pressure during laparoscopic surgery in head-up or head-down position

BACKGROUND: The abdominal insufflation and surgical positioning in the laparoscopic surgery have been reported to result in an increase of airway pressure. However, associated effects on changes of endotracheal tube cuff pressure are not well established. METHODS: 70 patients undergoing elective laparoscopic colorectal tumor resection (head-down position, n = 38) and laparoscopic cholecystecomy (head-up position, n = 32) were enrolled and were compared to 15 patients undergoing elective open abdominal surgery. Changes of cuff and airway pressures before and after abdominal insufflation in supine position and after head-down or head-up positioning were analysed and compared. RESULTS: There was no significant cuff and airway pressure changes during the first fifteen minutes in open abdominal surgery. After insufflation, the cuff pressure increased from 26 ± 3 to 32 ± 6 and 27 ± 3 to 33 ± 5 cmH(2)O in patients receiving laparoscopic cholecystecomy and laparoscopic colorectal tumor resection respectively (both p < 0.001). The head-down tilt further increased cuff pressure from 33 ± 5 to 35 ± 5 cmH(2)O (p < 0.001). There six patients undergoing colorectal tumor resection (18.8%) and eight patients undergoing cholecystecomy (21.1%) had a total increase of cuff pressure more than 10 cm H(2)O (18.8%). There was no significant correlation between increase of cuff pressure and either the patient's body mass index or the common range of intra-abdominal pressure (10-15 mmHg) used in laparoscopic surgery. CONCLUSIONS: An increase of endotracheal tube cuff pressure may occur during laparoscopic surgery especially in the head-down position

Prevalence of Pediculus Capitis Infestation Among School Children of Chinese Refugees Residing in Mountainous Areas of Northern Thailand

An epidemiologic survey of Pediculus capitis infestation among Akka aboriginal and Han children of Chinese refugees living in mountainous areas at elevations of 1,100 to 1,400 m in Chiang-Rai Province of northern Thailand was conducted during January 2003. Of the 303 children examined, 43 (14.2%) had P. capitis infestation. The overall infestation rate for P. capitis in Akka children (29.3%, 12/41) was significantly higher than that in Han children (11.8%, 31/262; c2 = 8.161, p = 0.002). The prevalence in Akka (52.2%, 12/23) and Han girls (19.7%, 31/157) was higher than that in Akka (0%) and Han boys (0%), respectively (p < 0.001), and the prevalence was higher in Akka girls than in Han girls (c2 = 10.978, p = 0.001). The high prevalence of P. capitis infestation among these girls was possibly due to poor environmental hygiene and unavailability of sufficient water