Experience with a Virtual Memory Based Data Acquisition System at CERN

This paper describes a Data Acquisition System which has been specifically designed to take advantage of modern operating systems. It is modular, structured as a set of independent tasks communicating via a shared data area. The design is based on the concept of circular buffers with associated data producer and (parallel) consumer tasks. By using privileged tasks in time critical areas, a fast and efficient system has been obtained: interrupt latency of less than 100 microseconds, and data transfer speeds essentially limited by hardware (CAMAC DMA or magnetic tape recording). The tasks may be distributed over different processors. For example, 16/32 bit multi-processors with a shared multi-port memory are used to implement systems where powerful data reduction and/or monitoring tasks are required. The system is in use at over 25 high energy and nuclear physics experiments at CERN and in other European laboratories.     

Fabrication of photonic crystals in silicon-on-insulator using 248-nm deep UV lithography

We demonstrate wavelength-scale photonic nanostructures, including photonic crystals, fabricated in silicon-on-insulator using deep ultraviolet (UV) lithography. We discuss the mass-manufacturing capabilities of deep UV lithography compared to e-beam lithography. This is illustrated with experimental results. Finally, we present some of the issues that arise when trying to use established complementary metal-oxide-semiconductor processes for the fabrication of photonic integrated circuits.     

Time-Delay-Integration Architectures in CMOS Image Sensors

Difficulty and challenges of implementing time-delay-integration (TDI) functionality in a CMOS technology are studied: synchronization of the samples forming a TDI pixel, adder matrix outside the array, and addition noise. Existing and new TDI sensor architecture concepts with snapshot shutter, rolling shutter, or orthogonal readout are presented. An optimization method is then introduced to inject modulation transfer function and quantum efficiency specification in the architecture definition. Moderate spatial and temporal oversamplings are combined to achieve near charge-coupled device (CCD) class performances, resulting in an acceptable design complexity. Finally, CCD and CMOS dynamic range and signal-to-noise ratio are conceptually compared.     

Modeling and Experimental Verification of the Dynamic Interaction of an AFM-Tip With a Photonic Crystal Microcavity

We present a transmission model for estimating the effect of the atomic-force microscopy tapping tip height on a photonic crystal microcavity (MC). This model uses a fit of the measured tip-height-dependent transmission above a ldquohot spotrdquo in the MC. The predicted transmission versus average tapping height is in good agreement with the values obtained from tapping mode experiments. Furthermore, we show that for the existing, nonoptimized structure, the transmission coefficient can be tuned between 0.32 and 0.8 by varying the average tapping height from 26 to 265 nm. A transmission larger than that of the undisturbed cavity at resonance was observed at specific tip locations just outside the cavity-terminating holes.     

Plasma for cancer treatment: How can RONS penetrate through the cell membrane? Answers from computer modeling

Plasma is gaining increasing interest for cancer treatment, but the underlying mechanisms are not yet fully understood. Using computer simulations at the molecular level, we try to gain better insight in how plasma-generated reactive oxygen and nitrogen species (RONS) can penetrate through the cell membrane. Specifically, we compare the permeability of various (hydrophilic and hydrophobic) RONS across both oxidized and nonoxidized cell membranes. We also study pore formation, and how it is hampered by higher concentrations of cholesterol in the cell membrane, and we illustrate the much higher permeability of H2O2 through aquaporin channels. Both mechanisms may explain the selective cytotoxic effect of plasma towards cancer cells. Finally, we also discuss the synergistic effect of plasma-induced oxidation and electric fields towards pore formation.     

Experimental demonstration of high coupling efficiency between wide ridge waveguides and single-mode photonic Crystal waveguides

The experimental demonstration of a high efficiency coupling technique based on setting a single defect within a photonic crystal (PhC) taper is reported. The samples were fabricated on a Silicon-on-insulator substrate and a 3-/spl mu/m-wide ridge waveguide was used to couple the light into and out of a single-mode PhC waveguide. Transmission efficiencies higher than 70% for wavelengths at 1.55 /spl mu/m are demonstrated which sharply improves the transmission efficiency achieved with butt-coupling and conventional PhC tapers.     

Radiation dose vs. image quality for low-dose CT protocols of the head for maxillofacial surgery and oral implant planning

The goal of this study was to determine the acquisition parameters for a low-dose multi-slice CT protocol and to compare the effective dose and the image quality of this low-dose protocol with the image quality of a clinical multi-slice CT protocol, routinely used for visualisation of the head. The low-dose protocol was derived from a clinical multi-slice CT protocol by lowering mA s and kV and increasing the pitch. The low-dose protocol yielded a dose reduction from 1.5 to 0.18 mSv for a multi-slice CT scan of the whole head, whereas noise in the low-dose CT images was increased. For bone segmentation, noise could be reduced by use of a non-linear edge preserving smoothing filter. Tests on ESP and skull phantom indicated that the accuracy of the measurements on low-dose CT is acceptable for image-based planning of maxillofacial and oral implant surgery, reducing the dose by a factor of 8.