Remote readable ID tags are interest for their uses in various fields. In previous papers the author proposed the application of a new ID tag a s an intelligent pile in a location-detection system. This ID tag consists of a magnetic tape encoded by the magnetic head, a magnetostrictive strip that resonates at predetermined frequencies according to the encoded pattern for identification, and a housing for both of these components. Examination of the characteristics of this ID tag, especially as regards the capacity and the reading range, showed that encoding with a magnetic pattern is effective for both sinusoidal and rectangular patterns. A reading distance of about 60 cm was sufficient for identifying several patterns, and a distance of about 50 cm for was sufficient 20 bits, which can be obtained by using multiple strips. The operation temperature is from -20°C to 60°C.

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The dependences of magnetic properties of Fe-N and Fe-Ti-N thin films on nitrogen partial pressure over total sputtering pressure ( P_N2 / P_Totai ) were studied, and the effect of annealing on Fe-Ti-N thin films was investigated. Thin films were prepared with a dc magnetron reactive sputtering apparatus, using a composite type of target. The coercivity of Fe-Ti-N films was smaller than that of Fe-N films when P_N2 / P_Totai was more than 1% . The minimum value of the coercivity for Fe-Ti-N films was 2.3 Oe in the easy magnetization direction and 1.25 Oe in the hard magnetization direction when P_N2 / P_Totai was 2.5%, while it was 4.5 Oe for Fe-N films when P_N2 / P_Totai was 1%. Annealing at 400°C minimized the coercivity of the Fe-Ti-N film at 1.3 Oe in the easy magnetization direction and 0.9 Oe in the hard magnetization direction.

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The X-ray reflectivity method using a Co-K_β line was used to analyze the layered structure of multilayers consisting of Co, Cu, CoFe, and NiFe layers. The thickness and interface width values of each layer can be obtained more accurately than in the conventional method using a Cu-K_αline, because of the anomalous dispersion effect, which enhances the X-rays reflected from the interfaces of the Co and CoFe layers. The value of δ for each layer at the Co-K_β X-ray wavelengh was obtained from the refractive index 1-δ by analysis of the reflectivities. The δ values of Co, Cu, and NiFe were within 2% of the value calculated fom the bulk density. Careful analysis of the Co / Cu / CoFe / NiFe multilayers by the least-squares method showed that the layer thickness of 1 nm can be refined.

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The present paper describes the effect of cell surface sialic acid on the orientation of motile and killed sperm of cattle in a 5400-G magnetic field. Cattle sperm collected from six bulls was placed in the medium. The semen suspensions were divided into motile, freeze-killed, and naturally dead sperm samples. An aliquot of the sperm samples were incubated with an added 1.0 mg / ml neuraminidaseat 30°C for 1 hour. Neuraminidase-treated and nontreated samples were exposed continuously for 24 hours to a magnetic field of 5400 G at 38°C. Neuraminidase treatment enhanced the orientation of the sperm. Naturally dead sperm treated with neuraminidase and exposed to the mgnetic field had the highest percentage of orientation. These findings suggest that a negatively charged cell surface inhibits sperm from orientating. However, freezekilled sperm had a lower percentage of orientation than naturally dead and motile sperm.

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The frequency characteristics of the head field were studied by simulation in order to design a high-performance thin-film write head for higher frequencies. Since the 3D analysis necessary for accurate consideration of magnetic nonlinearity and eddy current takes an extremely long CPU time, we developed an advanced 2D finite element program in which the reluctance and resistivity in the head core and the gap at coils were modified by taking account of the tapered shape effect of the upper yoke. It was confirmed in several cases that the computed results given by our model were consistent with 3D calculations. The relationships between the high-frequency characteristics of the write field and both the head shape and the material properties were investigated. We showed that the larger B_sand the thicker pole film make the field larger at relatively low frequencies, and that the increase in the resistivity and the decrease in the yoke length are very effective for improving the high-frequency performances. These results can be explained by simply assuming that the highfrequency permeability decreases in proportion to the eddy current.

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A superconducting magnetic shielding enclosure made of a bithmus-strontium-based high-critical-temperature superconducting material was formed to have better magnetic noise rejection at low frequencies than conventional magnetic shielding. To evaluate its efficiency, short- and middle-latency auditory evoked fields (SLAEFs and MLAEFs), which have weak amplitudes compared with other longlatency auditory evoked fields such as N1m, were measured. Measurements were made for three subjects with normal hearing in response to auditory clicks in the left ear. Multiple recordings were made at different locations over both lateral sides of the head, using a 7-ch SQUID with magnetometer coils. SLAEF and MLAEF components were observed at latencies of 6(M6), 10, 15, 20, and 30 ms in all subjects. Calculation of an equivalent current dipole source suggested that the source of M6 is located deep in the brain. The results are discussed alone with previous measurements of SLAEFs in terms of the response from the brainstem.

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