Hidden-Action in Network Routing

In communication networks, such as the Internet or mobile ad-hoc networks, the actions taken by intermediate nodes or links are typically hidden from the communicating endpoints; all the endpoints can observe is whether or not the end-to-end transmission was successful. Therefore, in the absence of incentives to the contrary, rational (i.e., selfish) intermediaries may choose to forward messages at a low priority or simply not forward messages at all. Using a principal-agent model, we show how the hidden-action problem can be overcome through appropriate design of contracts in both the direct (the endpoints contract with each individual router directly) and the recursive (each router contracts with the next downstream router) cases. We further show that, depending on the network topology, per-hop or per-path monitoring may not necessarily improve the utility of the principal or the social welfare of the system.     

A geometry-based error estimation for cross-ratios

For choosing specific cross-ratios as 2D projective coordinates in various computer vision applications, a reasonable error analysis model is usually required. This investigation adopts the assumption of normal distribution for positioning errors of point features in an image to formulate the error variances of cross-ratios. Based on a geometry-based error analysis, a straightforward way of identifying the cross-ratios with minimum error variances is proposed. Simulation results show that the proposed approach, as well as a further simplified alternative, yield much better estimations of minimum error variances in terms of accuracy, cost, and stability compared with some other methods, e.g., the one based on the rule given by Georis et al. (IEEE Trans. Pattern Anal. Mach. Intell. 20 (4) (1998) 366). Some causes of the performance differences in the estimations are explained using a special configuration of point features.     

Colloidal silica removal in coagulation processes for wastewater reuse in a high-tech industrial park.

Four experiments of coagulation and flocculation were conducted to investigate the characteristics of colloidal silica removal in a high-tech industrial wastewater treatment plant for reclamation and reuse of the effluent. Experimental results illustrated that poly-aluminium chloride (PACl) showed higher performances on colloidal silica removal than alum. Interestingly, the two coagulants demonstrated the same capacity on silica removal. The specific silica removal capacity was approximately 0.135 mg SiO2/mg Al2O3 when the dosage of coagulants was in the range 30-150 mg/L Al2O3. In addition, the silica was reduced significantly at the condition of pH above 8. Experimental data implied that precipitation of aluminium flocs was the major mechanism for colloid silica removal in PACl and alum coagulation, besides, charge adsorption was also important for improving removal efficiency. Moreover, the addition of polyacrylic acid (PAA) as a flocculant could slightly advance silica removal in the PACl coagulation. The combined PACl/PAA/flocs coagulation was effective for the removal of colloidal silica, soluble COD, and turbidity and also suitable as a pretreatment unit in wastewater reclamation and reuse processes.     

The role of estrogen in female urinary incontinence and urogenital aging: a review

Urogenital aging is a complex of urogenital symptoms involving the lower urinary tract, the genital tract and the pelvic floor. These symptoms involve hypoestrogenism in the menopausal woman. This review concludes that irritative urinary and local vaginal symptoms are quite amenable to estrogen therapy. Urinary incontinence is thought to be benefited by treatment with estrogen, although controversy exists. There is a limited role for estrogen in problems of urogenital prolapse, rectal symptoms, and sexuality in menopause.     

Image compression in digital mammography: effects on computerized detection of subtle microcalcifications

Our previous receiver operating characteristic (ROC) study indicated that the detection accuracy of microcalcifications by radiologists is significantly reduced if mammograms are digitized at 0.1 mm x 0.1 mm. Our recent study also showed that detection accuracy by computer decreases as the pixel size increases from 0.035 mm x 0.035 mm. It is evident that very large matrix sizes have to be used for digitizing mammograms in order to preserve the information in the image. Efficient compression techniques will be needed to facilitate communication and archiving of digital mammograms. In this study, we evaluated two compression techniques: full frame discrete cosine transform (DCT) with entropy coding and Laplacian pyramid hierarchical coding (LPHC). The dependence of their efficiency on the compression parameters was investigated. The techniques were compared in terms of the trade-off between the bit rate and the detection accuracy of subtle microcalcifications by an automated detection algorithm. The mean-square errors in the reconstructed images were determined and the visual quality of the error images was examined. It was found that with the LPHC method, the highest compression ratio achieved without a significant degradation in the detectability was 3.6:1. The full frame DCT method with entropy coding provided a higher compression efficiency of 9.6:1 at comparable detection accuracy. The mean-square errors did not correlate with the detection accuracy of the microcalcifications. This study demonstrated the importance of determining the quality of the decompressed images by the specific requirements of the task for which the decompressed images are to be used. Further investigation is needed for selection of optimal compression technique for digital mammograms.     

Localization of interferon-gamma and Ia-antigen in T cell line-mediated experimental autoimmune encephalomyelitis

This study reports the cellular localization of interferon-gamma (IFN-gamma) and MHC class II antigen (Ia) in the spinal cord of rats with experimental autoimmune encephalomyelitis induced by adoptive transfer of myelin basic protein-specific T cells. Numerous IFN-gamma-positive cells, stained with two different monoclonal antibodies against IFN-gamma, were present from days 3 to 7 after cell transfer. Their number was greatly reduced on day 10. A subpopulation of T cells was IFN-gamma positive. Moreover, a large number of ED1-positive macrophages contained IFN-gamma immunoreactivity. The transient presence of immune cells containing IFN-gamma immunoreactivity in experimental autoimmune encephalomyelitis suggests a pathogenic role of this cytokine in immune-mediated demyelination of the central nervous system.     

Optical gain of strained wurtzite GaN quantum-well lasers

A theory for the electronic band structure and the free-carrier optical gain of wurtzite-strained quantum-well lasers is presented. We take into account the strain-induced band-edge shifts and the realistic band structures of the GaN wurtzite crystals. The effective-mass Hamiltonian, the basis functions, the valence band structures, the interband momentum matrix elements, and the optical gain are presented with analytical expressions and numerical results for GaN-AlGaN strained quantum-well lasers. This theoretical model provides a foundation for investigating the electronic and optical properties of wurtzite-strained quantum-well lasers.     

碳掺杂β-FeSi2薄膜的电子显微学研究

本文利用透射电子显微镜对离子注入合成的β-FeSi2和β-Fe(C,Si)2薄膜进行了对比研究.电镜观察结果表明,选择C作为掺杂元素,能够得到界面平直、厚度均一的高质量β相薄膜,晶粒得到细化,β-FeSi2层稳定性提高.尤其在60kV、4×1017ions/cm2条件下注入直接形成非晶,在退火后会晶化为界面平滑、厚度均匀的β-FeSi2薄膜.因此从微结构角度考虑,引入C离子有益于提高β-FeSi2薄膜的质量.     

The radiotherapy of inoperable non-small-cell bronchial carcinoma. A retrospective analysis of 427 cases

BACKGROUND: The influence of tumor and patient characteristics on survival as well as acute normal tissue toxicity was retrospectively analyzed. PATIENTS AND METHODS: 427 patients with inoperable non-small cell lung cancer were retrospectively analyzed. Two thirds received a total dose of at least 70 Gy, and one third was irradiated with 60 to 66 Gy (2.0 to 2.5 Gy per fraction; split-course technique). 92% had a Karnofsky performance index of > or = 80%. Kaplan-Meier survival curves were generated and comparisons were made by the log-rank test. Prognostic factors were adjusted for by a proportional hazards analysis. RESULTS: Five-year survival rates (+/- SE) and the median survival times (95% confidence interval) were 2 +/- 2% and 11.1 months (9.1 ... 14.5) after 60 to 66 Gy; 8 +/- 2% and 14.9 months (13.3 ... 16.5) after 70+ Gy. The difference was significant in univariate (p = 0.0013) and multivariate analysis (p = 0.0006). Tumor stage (p = 0.0029: I + II > III; IIIA > IIIB) and gender (p = 0.0387: female > male patients) reached significance in multivariate analysis. Acute pneumonitis and esophagitis were observed in 11% and 9% of cases. CONCLUSIONS: Inoperable non-small cell lung cancer stage I to IIIA should be treated in a curative intention with total doses of about 70 Gy. This is feasible with acceptable normal tissue toxicity. Stage IIIB patients have a particular bad prognosis and should only be treated palliatively.     

Solitary, central neurofibroma of the mandible: a case report

A case of Solitary Central Neurofibroma in a 53 years old female is reported. This is an apparently single primary lesion, in which physical and Radiological examination failed to reveal other bony lesions or the stigmata of multiple neurofribomatosis.