A diffuse reflectance spectroscopy-based method to score fibrosis in paraffin-preserved human liver specimens has been developed and is reported here. Paraffin blocks containing human liver tissue were collected from the General Hospital of Mexico and included in the study with the patients' written consent. The score of liver fibrosis was determined in each sample by two experienced pathologists in a single-blind fashion. Spectral measurements were acquired at 450-750 nm by establishing surface contact between the optical probe and the preserved tissue. According to the histological evaluation, four liver samples showed no evidence of fibrosis and were categorized as F0, four hepatic specimens exhibited an initial degree of fibrosis (F1-F2), five liver specimens showed a severe degree of fibrosis (F3), and six samples exhibited cirrhosis (F4). The human liver tissue showed a characteristic diffuse reflectance spectrum associated with the progressive stages of fibrosis. In the F0 liver samples, the diffuse reflection intensity gradually increased in the wavelength range of 450-750 nm. In contrast, the F1-F2, F3, and F4 specimens showed corresponding 1.5-, 2-, and 5.5-fold decreases in the intensity of diffuse reflectance compared to the F0 liver specimens. At 650 nm, all the stages of liver fibrosis were clearly distinguished from each other with high sensitivity and specificity (92-100%). To our knowledge, this is the first study reporting a distinctive diffuse reflectance spectrum for each stage of fibrosis in paraffin-preserved human liver specimens. These results suggest that diffuse reflectance spectroscopy may represent a complementary tool to liver biopsy for grading fibrosis.

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Abstract-Within power generation, ageing assets and an emphasis on more efficient operation of power systems and improved maintenance decision methods has led to a growing focus on asset prognostics. The main challenge facing the implementation of successful asset prognostics in power generation is the lack of available run-to-failure data. This paper proposes to overcome this issue by use of full scope high fidelity simulators to generate the run-to-failure data required. From this simulated failure data a similarity based prognostic approach is developed for estimating the Remaining Useful Life of a valve asset. Case study data is generated by initializing prebuilt industrial failure models within a 970MW Pressurized Water Reactor simulation. Such full scope high fidelity simulators are mainly operated for training purposes, allowing personnel to gain experience of standard operation as well as failures within a safe, simulated operating environment. This research repurposes such a high fidelity simulator to generate the type of data and affects that would be produced in the event of a fault. The fault scenario is then run multiple times to generate a library of failure events. This library of events was then split into training and test batches for building the prognostic model. Results are presented and conclusions drawn about the success of the technique and the use of high fidelity simulators in this manner.Index Terms-Model-based prognostics, remaining useful life, high fidelity simulation, power generation,