A study on read‐back signal degradation of a pseudo‐contact head during seek motion of a hard disk drive

The read‐back signal degradation in seek motion with a pseudo‐contact head in a hard disk drive was studied. It was found by AES analysis that the pole tip surface of NiFe was covered with a decomposed layer of NiFe and carbon following seek motion. The read‐back signal degradation became larger with increasing thickness of the decomposed layer. An MFM study of the seek‐tested pole tip surface showed that the magnetic properties of the pole tip surface deteriorated by seek motion, and that the read‐back signal degradation increased with increase of deterioration of the magnetic properties of the pole tip surface. These results suggest that either the poor permeability of the decomposed layer on the pole tip surface and increase of spacing between the fresh pole tip surface under the decomposed layer and the disk surface decrease the flux flow from the disk magnetic layer into the pole tip, or that the decomposed layer on the gap short‐circuits the flux flow. It was found that the additive, cyclotriphosphazene, in a lubricant film, and a protective layer of carbon on a slider surface drastically reduced degradation. This revised version was published online in June 2006 with corrections to the Cover Date.     

The association between serum levels of Th cytokines and rhinoconjunctivitis caused by methyltetrahydrophthalic anhydride

BACKGROUND: There are few epidemiologic studies on the association between serum levels of T helper (Th) cytokines and allergic symptoms caused by sensitizing agents. METHODS: A population of 147 workers from two condenser plants using epoxy resin with methyltetrahydrophthalic anhydride (MTHPA) underwent a questionnaire survey and serologic investigations. Total and MTHPA-specific IgE levels were measured by the Pharmacia CAP System, and serum levels of interleukin (IL)-4, IL-13, and interferon-gamma (IFN-gamma) by enzyme immunoassay. RESULTS: A significant association was found between work-related eye and nasal symptoms and a range of atopic characteristics, including the frequency of positive specific IgE, specific and total IgE levels, and IL-4 levels. A positive correlation was observed between levels of IL-4 and IL-13 (r=0.42). Furthermore, multiple logistic analysis revealed significant contributions of specific IgE and IL-13 to the work-related symptoms. A similar but nonsignificant association was also found for IL-4 (P=0.07). On the other hand, a multiple regression model with specific IgE levels as a dependent variable showed a significant association with total IgE, but not with IL-4, IL-13, and IFN-gamma. CONCLUSIONS: These results suggest that work-related eye and nasal symptoms are closely related to specific IgE antibodies, and that allergic responses, mediated by IgE, to MTHPA may lead to a shift in the balance between Th1 and Th2 cells.     

A numerical study of the effects of piston head configurations on stratified mixture formation in gasoline direct-injection engines

In this paper, the characteristics of flow and spray motions affected by from piston head configurations were investigated numerically. Calculations were carried out from intake process to the end of compression. GTT (Generalized Tank and Tube method) code, which includes a third order upwind Chakravarthy-Osher TVD scheme andk-ε turbulence model with fuel spray analysis was used for the calculations. As a results, piston heads with smaller radii of curvature were found to give stronger reverse tumble than those with larger radii of curvature. Similar results are shown in the convection and diffusion of fuel sprays.     

Seismic reflector imaging by prestack time migration in the Kakkonda geothermal field, Japan

We show that a prestack migration method improves the S/N ratio of seismic reflection profiling in the Kakkonda geothermal field where seismic reflection data are of poor quality. We use non-iterative prestack time migration (PSTM), which does not require multiple iterations to determine the velocity structure for prestack time migration. The optimum constant migration velocity can be determined at each image point from a migration velocity analysis based on primary diffraction patterns. Our results delineate a strong reflector beneath a zone of high seismicity. According to the correspondence between the fracture distribution, the distribution of microearthquakes, and geothermal structure, this reflector is interpreted to be a zone of low-angle fractures saturated with hydrothermal fluids, and to be strongly controlled by the geothermal structure.     

Macromonomer formation by sterically hindered radical polymerization of methyl acrylate trimer at high temperature

Polymerization of the unsaturated trimer of methyl acrylate (MAT) was carried out by radical means at 70-130 °C. Fragmentation of propagating radicals resulting in ω-unsaturated end groups was studied as a synthetic route to macromonomers by radical polymerization. The ratios of the propagation rate constant to the fragmentation rate constant were 7.15 and 0.94 at 50 and 130 °C, respectively. MAT polymerization at 130 °C or above is suppressed by fragmentation of the propagating radical and the low ceiling temperature to facilitate efficient introduction of the unsaturated end groups. Copolymerization between MAT and macromonomer resulted in a small amount of polymer of higher molecular weight than the main polymeric product. Homopolymerization of MAT and its copolymerization with macromonomer appear to be influenced by rapid fragmentation, which renders the addition step reversible. This mechanism would regulate the chain length of the polymer and limit further reaction of the end group.     

Analysis of lipid classes and the fatty acid composition of the salted fish roe food products,Ikura, Tarako,Tobiko and Kazunoko

This study was designed to clarify the content of lipid classes and the fatty acid composition of total lipids (TL), sterol esters (SE), triacylglycerols (TG), phospholipids (PL), phosphatidylcholine (PC), and phosphatidylethanolamine (PE) of the Japanese fish roe products, Ikura, Tarako, Tobiko and Kazunoko. The TL, total cholesterol, TG, and PL content of Ikura were higher than those of Tarako, Tobiko and Kazunoko. Kazunoko had the lowest cholesterol content among these roe products. PC was the main component in the PL class of each fish roe product. The main fatty acids of all roe products were 16:0, 18:1n−9, 20:5n−3, and 22:6n−3. Docosahexaenoic acid (22:6n−3) was rich in the TL, SE, TG, PL, PC and PE fractions of all roe products. In particulars the 22:6n−3 percentage of PC and PE fractions in Tobiko were higher than those of Ikura, Tarako and Kazunoko. These results indicate that the lipid from fish roe products may be a useful food source for maintaining human health.     

Effect of rebamipide, a novel antiulcer agent, on Helicobacter pylori adhesion to gastric epithelial cells

We examined regional cerebral blood flow (rCBF) during a long-term recognition memory task for words in schizophrenic patients and in healthy subjects using positron emission tomography (PET). The task was designed so that performance scores were similar in the patient and control subjects. This memory retrieval task did not increase rCBF in the patients' prefrontal cortex, precuneus and cerebellum as much as it did in the control group. These results point to a dysfunctional corticocerebellar circuit leading to poorly coordinated mental activity ('cognitive dysmetria'), which could explain the broad range of schizophrenic symptoms. In addition, other brain areas were more activated by the task in the patient group than in the control group and may form a compensatory network performing the memory retrieval task by assisting or replacing the dysfunctional cortico-cerebellar circuit.     

Posthyperventilatory steal response in chronic cerebral hemodynamic stress: a positron emission tomography study

BACKGROUND AND PURPOSE: The alteration of regional cerebral blood flow (CBF) during and after hyperventilation was measured using positron emission tomography (PET) to determine the circulatory response induced by daily respiratory changes in the cerebral area under chronic hemodynamic stress. METHODS: Three normal volunteers and 12 patients with an obstruction of major cerebral arteries underwent PET measurements of the CBF after an injection of H2(15)O: (1) in the resting condition, (2) during hyperventilation (HV scan), (3) 1 to 3 minutes after hyperventilation (post-HV scan), (4) during the inhalation of 5% CO2, and (5) after an injection of acetazolamide. Eleven patients also underwent a 15O gas study to measure CBF, oxygen extraction fraction (OEF), and cerebral blood volume (CBV). RESULTS: (1) In 9 patients, the CBF value in the post-HV scan was lower than that in the HV scan in 1 or more regions in the area of the obstructed arteries, although the PaCO2 level during the post-HV scan was higher than that during the HV scan in all patients. All control regions in the patients and in the normal volunteers showed an elevated CBF in the post-HV scan compared with the HV scan. (2) The negative post-HV response (posthyperventilatory steal) was prominent in 4 patients with moyamoya vessels and in another 5 patients with atherosclerotic disease who had PET evidence of hemodynamic stress (elevated CBV or OEF). (3) The regional pre- to post-HV change in CBF was significantly correlated with the CBF responses to acetazolamide and CO2. CONCLUSIONS: Vasodilatation after the termination of hyperventilation in the normal areas induces a steal response in the cerebral area suffering from hemodynamic stress and may cause profound hypoperfusion in everyday situations. This phenomenon may be important to our understanding of the clinical symptoms and the natural course of chronic cerebral occlusive disease bearing hemodynamic stress.