We present a novel Client-Weighted Medium-Transparent MAC (CW-MT-MAC) protocol with enhanced fairness service delivery properties accompanied by a low-loss Remote Access Unit (RAU) architecture for use in indoor, Gbps capable, 60 GHz Radio-over-Fiber (RoF) Wireless Local Access Networks (WLANs). Our approach relies on incorporating a Client Weighted Algorithm (CWA) in the optical capacity allocation mechanism employed in the MT-MAC scheme, so as to distribute the available wavelengths to the different antenna units according to the total number of active users served by each individual antenna. The protocol's throughput and delay fairness characteristics are evaluated and validated through both simulations and analytic modeling for saturated network traffic operational conditions. In addition, extended simulation-based performance analysis for nonsaturated network conditions and for different enduser distributions, traffic loads and available optical wavelengths at 1 Gbps data rates are presented. Our results confirm that complete throughput equalization can be achieved even for highly varying user population patterns when certain wavelength availability conditions are satisfied. At the same time, the presented scheme manages to equalize the average packet delays amongst packets generated by all RAUs while concurrently dropping the Packet Delay Variation (PDV) metric that is essential for Quality of Service (QoS) delivery. Finally the Manuscript received October 9, 2001.

An optical RAM row access gate followed by a column address selector for wavelength-division-multiplexing (WDM)-formatted words employing a single semiconductor optical amplifierVMach-Zehnder interferometer (SOA-MZI) is presented. RAM row access is performed by the SOA-MZI that grants random access to a 4-bit WDM-formatted optical word employing multiwavelength cross-phase-modulation (XPM) phenomena, whereas column decoding is carried out in a completely passive way using arrayed waveguide grating. Proof-of-concept experimental verification for both positive and negative logic access is demonstrated for 4 Â 10 Gb/s optical words, showing error-free operation with only 0.4-dBpeak-power penalty and requiring a power value of 25 mW/Gb/s.

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The aim of the present study was the investigation of radiographic findings in relation to lung function after occupational exposure to permissible levels of relatively pure chrysotile (0.5-3% amphiboles). We studied 266 out of the total 317 employees who have worked in an asbestos cement factory during the period 1968-2004 with chest x-ray, high-resolution computed tomography (HRCT) and lung function tests. Sensitivity of chest x-ray was 43% compared to HRCT. Abnormal HRCT findings were found in 75 subjects (67%) and were related to age, occupational exposure duration, and spirometric data. The presence of parenchymal or visceral pleural lesions (exclusively or as the predominant abnormality) was being accompanied by lower total lung capacity and diffusion capacity. HRCT was much more sensitive than chest x-ray for occupational chrysotile exposure. Lung function impairment was related with parenchymal but not with pleural HRCT abnormalities.

We demonstrate the Optical Board Simulator platform for optical PCB layout design and performance evaluation. Performance of two optical Blades is compared to CRAY-XK7 Blade for the FFTW benchmark, revealing significant throughput and latency improvements.