[Iterated Tikhonov Regularization for Spectral Recovery from Tristimulus].

Reflective spectra in a multispectral image can objectively and originally represent color information due to their high dimensionality, illuminant independent and device independent. Aiming to the problem of loss of spectral information when the spectral data reconstructed from three-dimensional colorimetric data in the trichromatic camera-based spectral image acquisition system and its subsequent problem of loss of color information, this work proposes an iterated Tikhonov regularization to reconstruct the reflectance spectra. First of all, according to relationship between the colorimetric value and the reflective spectra in the colorimetric theory, this work constructs a spectral reconstruction equation which can reconstruct high dimensional spectral data from three dimensional colorimetric data acquired by the trichromatic camera. Then, the iterated Tikhonov regularization, inspired by the idea of the pseudo inverse Moore-Penrose, is used to cope with the linear ill-posed inverse problem during solving the equation of reconstructing reflectance spectra. Meanwhile, the work also uses the L-curve method to obtain an optimal regularized parameter of the iterated Tikhonov regularization by training a set of samples. Through these methods, the ill condition of the spectral reconstruction equation can be effectively controlled and improved, and subsequently loss of spectral information of the reconstructed spectral data can be reduced. The verification experiment is performed under another set of training samples. The experimental results show that the proposed method reconstructs the reflective spectra with less spectral information loss in the trichromatic camera-based spectral image acquisition system, which reflects in obvious decreases of spectral errors and colorimetric errors compared with the previous method.

[Research on Developping the Colorimetric Correction Method Based on Wide Gamut Spectral Color Dataset].

In cross-media digital color imaging workflow, the colorimetric information transform among various digital medias always suffers from large transform errors, due to the difference among the lighting illuminants and the digital devices. Colorimetric correction aims at avoiding the colorimetric transform mismatch and thus improving the color transform accuracy comprehensively. Till now, two kinds of colorimetric transform methods have been proposed, which are the chromatic adaptation transform and the regression-based transform. However, since the color gamut of the training samples of such two method are both small, adopting those methods in colorimetric domain always leads to large colorimetric transform errors for the high saturated color regions. In this research, in order to reduce the large correction error in high saturated color regions, a modified colorimetric correction method basing on a wide gamut spectral dataset was proposed. The wide gamut spectral dataset was built by comprehensively collecting and producing typical spectral color samples and could provide optimal training samples for the existing regression based colorimetric correction model, with the help of gamut partition and optimal color purity choosing. By modifying the existing method with such samples, the colorimetric correction performance obviously improved. The experimental result shows that the modified colorimetric correction method performs significantly better than the existing methods and the colorimetric correction errors are successfully reduced by around 15% according to proposed method in form of CIEDE2000 color difference, while as for the high saturated color regions the reduction rate of the colorimetric correction errors approximately grows to 40%. The authors believe that the proposed method will provided effective support for the development of digital color imaging in near future.

Sirolimus as primary immunosuppressant for calcineurin inhibitor-related renal insufficiency after liver transplantation.

BACKGROUND: Calcineurin inhibitor-related renal toxicity affects patient and graft survival in transplant recipients. This study aimed to determine whether sirolimus is effective and safe in treating renal insufficiency related to tacrolimus after liver transplantation. METHODS: Tacrolimus for primary immunosuppression was used in 16 patients after liver transplantation. Patients with a creatinine level higher than 132.6 micromol/L were eligible for conversion to sirolimus. Simultaneously, the dose of tacrolimus was decreased to half. Blood urea nitrogen, creatinine, tacrolimus level, liver function and rejection episodes were monitored dynamically. RESULTS: All patients showed improvement of renal function after conversion to sirolimus. Blood creatinine level was reduced from 146.8+/-92.4 to 105.3+/-71.3 micromol/L (P<0.05). One patient had an acute rejection episode that was successfully treated with pulsed corticosteroids and low-dose tacrolimus. The side-effects of sirolimus included hyperlipidemia (4 patients) and leukocytopenia (2). CONCLUSION: Sirolimus can be safely used in liver transplant recipients suffering from tacrolimus-related renal insufficiency.

[Laparoscopy assisted total mesorectal excision for rectal cancer].

OBJECTIVE: To evaluate the feasibility of laparoscopy assisted total mesorectal excision (TME) for rectal cancer. METHOD: From March 2000 to November 2003,67 patients with rectal cancer received laparoscopy assisted TME,in whom 45 cases received anterior resection (AR),and 22 cases received abdominal perineal resection (APR). RESULTS: The operation was performed according to the rules of TME. The operative bleeding volume ranged from 10 to 50 ml. The operative time ranged from 2.5 to 5 hours without operative related death. Gastrointestinal decompression time ranged from 8 to 24 hours after operation. The time of intaking fluid food ranged from 24 to 48 hours after operation; the time of taking general activity ranged from 1 to 3 days after operation,and the defecating time ranged from 1 to 5 days after operation. The time of the hospital stay ranged from 7 to 10 days. All patients were followed up from 3 to 43 months except 3 patients. Two patients had local recurrence, including 1 patient died of local recurrence; 2 patients had liver metastases including 1 patient died of tumor metastasis but another was still alive. No metastasis and recurrence was found in 19 patients within follow - up time of one year. CONCLUSION: The laparoscopy assisted TME is a feasible approach for rectal cancer if surgeons have experience in open operation of laparoscopy assisted TME and good managing skills.