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In this work, the frequency response in magnetic tunnel junction (MTJ) heads was studied. Both stray capacitance and junction resistance, forming a low-pass-filter, have to be reduced to improve the cutoff frequency in MTJ heads. By employing an Ar gas cluster ion beam (GCIB) process, junctions grown on the magnetic shield show a resistance area product as low as 3.6 [Omega][micro][m.sup.2] and tunneling magneto-resistance over 14%. The dominant capacitance in common lead and shield MTJ heads was found mainly resulting from the shield-to-shield spacing, whose capacitance can be reduced by using an Si[O.sub.2] gap layer instead of [Al.sub.2][O.sub.3] layer and thus leading to an improved frequency response. Simple analysis indicates that a read amplifier design with low impedance could be helpful to realize a high data transfer rate, and a rate of around 800 Mbps for 100 Gbits/[in.sup.2] recording system can be thus expected. Index Terms--Common lead and shield, cut off frequency, data transfer rate, input impedance, magnetic recording/magnetic tunnel junction heads, stray capacitance.

Magnetic tunnel junction (MTJ) heads have been successfully fabricated using the free layer as flux guide to prevent electrical short during the definition of the air bearing surface (ABS). For a 6 Gbits/[in.sup.2] design, an output as high as 5740 [micro]Vpp was achieved for 3 mA sense current, and the output waveform was stable and noise free. Noise analysis confirmed that shot noise is prevailing in these MTJ heads, suggesting that the junction resistance has to be further reduced to challenge spin-valve heads in term of signal to noise ratio. Landau-Lifshitz-Gilbert simulations showed that for 20 Gbits/[in.sup.2] application, the flux guide height should not exceed 0. [micro]m. Index Terms--Magnetic recording/magnetic tunnel junction heads, front flux guide, shot noise, micromagnetic simulation.

An integrated thin film MI(magneto-impedance) sensor head constructed with a combination of a thin film NiFe MI element and thin film bias and negative feedback coils using a micro-plating technology, has been developed in order to solve the problems of an amorphous wire MI head. The sensor head showed a very high field-detection sensitivity of about 0.41%/A/m(33%/Oe) magnetized with pulse current and a small hysteresis for the change of an external field. We have fabricated a differential type sensor module using a pair of the thin film MI sensor heads. The output voltage of the sensor has a good linearity within the range of [+ or -] 80A/m, and the voltage was 25mV/A/m(2.0V/Oe), and has small thermal drift within 0.1A/m/ [degrees] C. The consumption power of the sensor module was 165mW. Index Terms -- MI, thin film MI sensor head, thin film bias and negative feedback coils, micro-plating technology, differential type sensor module

Objectives Patients with Parkinson's disease (PD) begin to lose weight several years before diagnosis, which suggests weight variation is associated with some factor(s) that precede the onset of motor symptoms. This study aimed to investigate the association of autonomic nervous system with body weight in patients with PD. Materials and methods The subjects were 90 patients with early de novo PD. We examined the associations of body mass index (BMI) with sympathetic nervous activity reflected in orthostatic intolerance or cardiac uptake of 123I-metaiodobenzylguanidine and parasympathetic nervous activity reflected in constipation or heart rate variability (HRV). Results Twelve patients (13.3%) were overweight (BMI>25 kg/m2), 62 patients (68.9%) were normal-weight (18.5≦BMI<25 kg/m2), and 16 patients (17.8%) were underweight (BMI<18.5 kg/m2). Underweight patients had greater disease severity and decrease in blood pressure on head-up tilt-table testing, higher cardiac washout ratio of 123I-metaiodobenzylguanidine, and lower HRV and complained of constipation more often than those with normal-weight or overweight patients. On multiple regression analyses, the correlation of these variables with BMI maintained statistical significance after adjustment for age, sex, symptom duration, and motor subtype. Conclusions Dysautonomia and disease severity are closely related to body weight independently of age, sex, symptom duration, and motor subtype. Dysautonomia may play a partial role on weight variation in the early stage of PD. [ABSTRACT FROM AUTHOR]