A method for monitoring head media spacing change in a hard disk drive using an embedded contact sensor

Growth in the demand for higher capacity hard disk drives has pushed the requirement for head-media spacing to sub-nanometer levels. The drop in operational clearance makes a head-disk interface more susceptible to potential head-wear and contamination related issues. Such degradation processes are often accompanied by a noticeable shift in the head-disk clearance. Hence monitoring an interface for a spacing change can be helpful in early detection of its imminent failure. In this paper, we present a method to detect the change in head-disk spacing using an embedded contact sensor (ECS). This technique involves the analysis of ECS dynamic response for an interface that is subjected to heater induced spacing modulations. As the head moves closer to the disk surface, the magnitude of the ECS frequency components can be used to determine the ‘characteristic spacing’ which can be used as a metric to detect any physical change for a given interface.

     

Experimental study of slider dynamics induced by contacts with disk asperities

Vertical vibrations at the slider leading edge exited by a disk asperity were investigated in a drive level system, using laser Doppler vibrometry and acoustic emission (AE) sensors. The flying height change at the leading edge of a thermal flying-height control slider was measured for different power inputs to the heater element. The maximum spacing change at the slider leading edge was found to be about 4 nm for an asperity of 26 nm height and 1.1 μm width. A method was investigated to produce “artificial asperities” on a disk surface using a nano-indentor. The geometry of the “artificial asperities” was characterized using an atomic force microscope. In addition, a spin stand was used to analyze the AE signal of slider vibrations induced by contacts with the “artificial asperities”. First and second pitch modes of the slider were observed.     

Selective inhibition of magnocellular vasopressin neurons by hypoosmolality: effect on histamine- and stress-induced secretion of adrenocorticotropin and prolactin

The innervation of the canine hip joint has become increasingly important in the treatment of hip dysplasia and hip arthrosis, since investigations proved that simple removal of periosteum around attachment of hip joint capsule, called denervation results in an instant analgesia and allows the dog to regain joyful freedom of movement. A macroscopic-anatomic examination of 16 canine hips furnished new findings and knowledge in the field of veterinary medicine on the sensitive innervation of the canine hip joint capsule. Accordingly, the craniolateral area of hip joint capsule is innervated by rami articulares of N. glutaeus cranialis, the caudolateral area by rami articulares of N. ischiadicus and the medial area by rami articulares of N. femoralis.     

Giant sequoia (Sequoiadendron giganteum (Lindl.) Buchholz) in Europe

Since 1853 seeds ofSequoiadendron giganteum (Lindl.) Buchholz found their way to Europe. Planted in botanical gardens, arboreta and parks Giant Sequoia survived to significant size in many countries of Western Europe. Today its growth surpasses that of all other softwoods known on the continent. The author analyzes its potential as a useful addition to forestry, stressing European experiences with geographic distribution, different climates, soils, genetic variability, increment and yield. Other aspects described are its wood quality, i.e. knottiness, width of annual rings, heartwood formation, fiberlength, specific gravity, strength properties, durability and the chance for an adequate utilization by the forest products industry.     

Professor Dr. Horst Schulz 65 Jahre alt

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Anisotropic Responsivity of AlGaN Metal–Semiconductor–Metal Photodetectors on Epitaxial Laterally Overgrown AlN/Sapphire Templates

Al_0.4Ga_0.6N metal–semiconductor–metal photodetectors on epitaxial laterally overgrown (ELO) AlN/sapphire templates show anisotropic device characteristics depending on the orientation of the electrode stripes with respect to the stripe pattern onto which the underlying ELO AlN buffer layers have been grown. With electrodes perpendicular to the stripes, a quantum efficiency (QE) of ～140 was found for 20-V bias at room-temperature. This gain is explained by carrier transport along channels with increased Ga content resulting from faceted growth at the steps of the ELO template. The resulting potential barrier is confirmed by the activation energy found for the temperature dependence of the QE. In contrast, photodetectors with electrodes running parallel to these channels do not show gain but have an enhanced QE at elevated bias voltage compared to devices on planar AlN buffer layers. This effect is attributed to different densities of threading dislocations in the absorber layer.     

Passively cooled 940 nm laser bars with 73% wall-plug efficiency at 70 W and 25/spl deg/C

940 nm laser bars with a vertical divergence of 27/spl deg/ (FWHM) and a filling factor of 30% were operated on passively cooled heatsinks at 25/spl deg/C. The maximum output power was 95 W, the maximum wall-plug efficiency was 73% at 70 W. Reliable CW and quasi-CW operation up to 98 W was demonstrated.     

Seroprevalence of GB virus C and persistence of RNA and antibody

Cercopithecus, the genus of guenons, is the largest of the African primate genera, and yet more than half of the species belonging to this group have never been the focus of a long-term field study. In this paper, I present data on group size and composition for a previously unstudied population of guenons on the Caribbean island of Grenada. The mona monkey, Cercopithecus mona, was introduced to Grenada from Africa approximately 200-300 years ago. Two types of social groups were found for Cercopithecus mona on Grenada: all-male groups consisting of two to four individuals and bisexual groups containing 5-32 individuals. All-male groups of Grenada mona monkeys contained any combination of juveniles, subadults, and/or adults. All-male groups were a common occurrence on Grenada but have never been reported for African C. mona and have been reported only in two other forest Cercopithecus species. Bisexual groups appeared to consist of one adult male, one to six adult females, subadult females, and juveniles and infants of both sexes. Even though no more than one adult male was ever seen in each bisexual group of monas on Grenada, other males were heard giving copulation calls simultaneously with resident adult male loud calls, suggesting that other males occasionally infiltrate bisexual groups.