Super-resolution (SR) effects of a thermo-chromic organic dye
mask layer are
investigated for a rewritable disk with a Ag–In–Sb–Te phase-change
recording layer.
Clear SR effects were recognized in both linear and radial directions
in the rewritable
disk, corresponding to a capacity of 10.3 GB in a 120 mm disk. A
carrier-to-noise ratio
over 35 dB was obtained at a short mark length of
0.2 µm. Crescent-shaped marks,
which are typically recognized in high-density magneto-optical (MO)
media, were
observed in the phase-change recording layer. The SR effects mainly
operate on the
reading process, resulting from a large non-linear transmittance
change in the organic dye.
Shear mode transmission through the skull has been previously proposed as a new trans-skull propagation technique for noninvasive therapeutic ultrasound (Clement 2004 J. Acoust. Soc. Am. 115 1356. The main advantage of choosing shear over longitudinal mode resides on the fact that there is less wavefront distortion with the former. In the present study, the regions of the brain suitable for shear-mode transmission were established for a simple focused ultrasound device. The device consists of a spherically curved transducer that has a focal length of 10 cm, an aperture between 30 • and 60 • and operates at 0.74 MHz. The regions suitable for shear-mode transmission were determined by the shear wave acoustic windows that matched the shape of the device acoustic field. The acoustic windows were calculated using segmentation and triangulation of outer and inner faces of skull from 3D-MRI head datasets. Nine heads of healthy adults were analyzed. The surface considered for the calculations was the head region found above the supraorbital margin. For every inspected point in the brain volume, the axis of the device was determined by the vector between this inspection point and a point located in the center of the brain. Numerical predictions of the acoustic field, where shear-mode conversion through the skull was considered, were obtained and compared to the case of water-only conditions. The brain tissue that is close to the skull showed suitable acoustic windows for shear waves. The central region of the brain seems to be unreachable using shear-mode. Analysis of the acoustic fields showed a proportional relation between the acoustic window for shear mode and the effective degree of focusing. However, this relation showed significant differences among specimens. In general, highly focused fields were obtained when the acoustic window for shear waves (A SW ) intersected more than 67% of the entering acoustic window (A TX ) of the device. The average depth from the inner surface of the skull showing this intersection value was 13 ± 10 mm (mean ± SD). The differences of the degree of focusing observed 0031-9155/07/247313+20$30.00
In orrer to clarify the magnetic properties of the initial growth region of C0 83 Cr 17 layers deposited on Cr undeday ers, very thin paramagnetic C0 67 Cr 33 intermediate layers, which possess the almost same crystallographic characteristics as C0 83 Cr 17 layer, were deposited as the intermediate layer between C0 83 Cr 17 and Cr layers. The paramagnetic C0 67 Cr 33 intermediate layers were effective to control the magnetic characteristics in the initial growth region of the C0 83 Cr 17 layer deposited on the 2000 A-thick Cr undedayer. The trilayered films with 50 A-thick C0 67 Cr 33 intermediate layer revealed higher Hcll and small SFD.
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