Classification of Events Violating the Safety of Physical Layers in Fiber-Optic Network Infrastructures.

Fiber-optic network infrastructures are crucial for the transmission of data over long and short distances. Fiber optics are also preferred for the infrastructure of in-building data communications. In this study, we use polarization analysis to ensure the security of the optical fiber/cables of the physical layer. This method exploits the changes induced by mechanical vibrations to polarization states, which can be easily detected using a polarization beam splitter and a balancing photodetector. We use machine learning to classify selected events that violate the safety of the physical layer, such as manipulation or temporary disconnection of connectors. The results show the resting state can be accurately distinguished from selected security breaches for a fiber route subjected to environmental disturbances, where individual events can be classified with nearly 99% accuracy.

Physical Layer Components Security Risks in Optical Fiber Infrastructures.

Optical fiber communications are essential for all types of long- and short-distance transmissions. The aim of this paper is to analyze the previously presented security risks and, based on measurements, provide the risk level evaluation. The major risk is the possibility of inserting a splitter into the optical distribution network and capturing a portion of the entire spectrum, i.e., all channels in the optical fiber. Another significant security risk is crosstalk on multiplexers in networks with wavelength division multiplexing. The paper covers the macrobend attenuation evaluation of fiber and back-reflection measurements. Based on the measurements, risks were evaluated for both point-to-point and point-to-multipoint networks and, lastly, the paper covers crosstalk measurements of an optomechanical switch. Finally, all individual risks are evaluated according to the severity, and a proposal for risk minimization is provided.

Gemcitabine monotherapy in patients with locally advanced or metastatic pancreatic cancer: a prospective observational study.

Pancreatic cancer has one of the worst prognosis of any malignant disease. Systemic therapy is often administered because the disease is usually detected at advanced stages. Gemcitabine (Gemzar trade mark, Eli Lilly & Co.) has proven activity in the treatment of pancreatic cancer. Gemcitabine 1000 mg/m(2) was given on days 1, 8 and 15, every 4 weeks. A total of 100 chemonaive patients with locally advanced or metastatic pancreatic cancer were enrolled; 32 and 68% had stage III and IV disease, respectively. The average number of administered cycles was 3.5 (range: 1 - 12). The overall response rate was 13%, with 13 partial responders. The median time to progression was 13.5 weeks (range: 3 - 56; 95% CI = 12 - 14). The median survival was 32 weeks (range: 4 - 104; 95% CI = 27 - 36). Clinical benefit response was acheived for 26 patients (26%). Grade 3/4 haematological toxicities occurred infrequently (anaemia: 5%; neutropenia: 8% and thrombocytopenia: 3% of patients). Grade 3/4 non-haematological toxicities were not observed. There were no treatment-related deaths. Gemcitabine treatment of patients with locally advanced or metastatic pancreatic cancer is effective and well-tolerated.