Rapid bone resorption adjacent to hydroxyapatite-coated implants

This paper describes rapid bone resorption in the peri-implantitis of HA implants based on both our clinical observations of and histological research on extracted dense hydroxyapatite (HA) implants. The surfaces of extracted HA implants were rough, although they were smooth at fixture placement. Plaque formed on the necks of the implants, whereas little plaque was seen on the bottoms. The plaque consisted of cocci and rods, including filamentous bacteria. Few spirochetes were observed. Although surrounding bone was formed rapidly around the HA implant, bone thickness gradually decreased compared with the titanium implant. These facts suggest that the rigid biointegration of HA with the thin surrounding bone--that is, the overstressing of the bone--causes rapid bone resorption rather than plaque accumulation on HA.     

Imaging of myocardial perfusion and metabolism with positron emission tomography

Positron emission tomography (PET) has been providing new information in the diagnosis and the pathophysiological assessment of heart diseases. The PET tracers commonly used in Japan are 13N-ammonia, 18F-fluorodeoxyglucose (FDG) for imaging of myocardial perfusion and metabolism, respectively. Measurement of regional myocardial blood flow by 13N-ammonia dynamic PET scan and a compartment model analysis is applied to the functional estimation of coronary stenotic lesions and the detection of perfusion abnormalities in hypertrophic heart diseases, familial hyperchlesterolemia and other diseases with possible microvascular lesions. 18F-FDG is commonly used to differentiate ischemic but viable tissue from myocardial scar in coronary artery disease and also used to detect cardiac tumor and the cardiac involvement in sarcoidosis. In addition to these two tracers, 11C-acetate is now expected to provide the clinical analysis of pathophysiology of heart failure by estimating the efficiency of energy conversion of the heart into external work.     

Light-induced electrical responses of dried chromatophore film: effect of the addition of cytochrome c

Chromatophores, photosynthetic membranes of photosynthetic bacteria, were isolated and cast on a transparent electrode to form films. The absorption spectrum of the film was similar to that of the native chromatophore. This indicated that the chromophore-protein structures were maintained through drying. Electrical transients of the film on the light pulsed excitation were examined. The amplitude and decay of the electrical transient of the film were altered by the addition of horse heart cytochrome c to the chromatophore of Rhodobacter sphaeroides R-26, which lacks the reaction centre-bound cytochrome c. The addition of cytochrome c into the film resulted in an increase in the light-induced current and a decrease in current decay.     

Detectivity studies of SMD-packaged ZnSSe and ZnMgS UV detectors

The 1/f noise and shot noise studies were carried out on molecular beam epitaxy (MBE)-grown ZnS_0.85Se_0.15 and Zn_0.43Mg_0.57S ultraviolet (UV) detectors packaged in surface mount lead frames. Three ZnS_0.85Se_0.15 detectors with different thicknesses of the active layer and the top electrode pad were used. The highest onset of reverse bias for the appearance of 1/f noise is ?27.5 V, and the highest dark resistances at zero bias is R₀=3.7×10¹³ Θ. The observed difference in their noise performance implies that the increase of the thicknesses of both the active layer and the top electrode pad can significantly lower the noise levels and in turn lead to higher detectivity. The best detectivity achieved is 8.75×10¹³ cm Hz^1/2 W^?1 in a ZnS_0.85Se_0.15 detector with an active layer of 5000 Å and a top electrode pad of Cr (50 Å)/Au (8000 Å). The typical detectivity achieved on Zn_0.43Mg_0.57S devices that have an active layer thickness just exceeds the critical thickness of phase transition is 1.54×10¹² cm Hz^1/2 W^?1.     

Semiconductor-metal phase transition of iron disilicide by laser annealing and its application to form device electrodes

Phase transition of semiconducting β-FeSi₂ to metallic α-FeSi₂ has been realized by laser annealing (Nd:YAG laser, λ=1.064 μm) in order to form ohmic electrodes for β-FeSi₂ devices. The starting samples were 200-nm-thick β-FeSi₂ films formed on Si substrates by reactive deposition epitaxy method. XRD and micro-Raman spectroscopy measurements confirmed the successful phase transition. The electrical resistivity of the α-FeSi₂ film was 2.0×10⁻⁴ Ω·cm, three orders lower than that of the original β-FeSi₂ film (1.4×10⁻¹ Ω·cm). Cross-sectional TEM images and electron diffraction patterns indicated that the upper ∼100 nm of the annealed film was changed to α-FeSi₂ while the lower part remained to be β-FeSi₂. α-FeSi₂ layer had good ohmic contact with β-FeSi₂. A testing p-β-FeSi₂/n-Si diode with laser-annealed α-FeSi₂ as the electrode on β-FeSi₂ showed the same rectifying characteristic as that using Al-evaporated electrode.     

A new core

This article discusses motors for compressors in domestic air conditioners, an area in which there is a strong demand for high efficiency and also reports the results of the efficiency improvement and productivity of a new core structure. An innovative core structure and manufacturing method boosts efficiency of permanent-magnet motors. This article presents the close relationship between the motor characteristics and the manufacturing method and indicates a way to improve both motor characteristics and the productivity. To pursue further improvement in motor performance by improving the coil space factor further using the joint-lapped core and manufacturing cores with smaller magnetic resistance.     

Optimal feedback control for route tracking with a bounded-curvature vehicle

The problem of driving a vehicle along a given path is considered. The vehicle is supposed to move forward only, with a given velocity profile, and to have a bounded turning radius. Such a model, also known as 'Dubins' vehicle', is relevant to the kinematics of road vehicles as well as aircraft cruising at constant altitude, or sea vessels. We consider the optimal control problem consisting of minimizing the length travelled by the vehicle starting from a generic configuration to connect to a specified route. A feedback law is proposed, such that straight routes can be approached optimally, while the system is asymptotically stabilized. Experimental results are reported showing real-time feasibility of the proposed approach.     

Modeling and attitude control analysis of a ducted-fan micro aerial vehicle

This paper deals with the aerodynamic modeling of a ducted fan Vertical TakeOff and Landing (VTOL) Unmanned Aerial Vehicle (UAV) and the problem of attitude stabilization when the vehicle is remotely controlled by a human pilot in presence of crosswind. The main aerodynamic elements, which are inherent to the presence of the duct and explain the flight dynamics of this kind of vehicle, are first presented. Then, an attitude control is designed from a linearization of the dynamic model around the hovering flight equilibrium. As the vehicle is axis-symmetric, the pitch and the roll dynamics have a similar expression. For this reason, the presentation is focused on the design of the pitch controller. Similar results can be directly deduced for the roll. Experiments, led on the HoverEye platform designed by Bertin Technologies, show that the proposed attitude control is sufficient to open a large secure flight envelope.     

Commonalities and differences in the working memory components underlying letter and category fluency tasks: A dual-task investigation.

This study used a dual-task interference paradigm to test the hypothesis that different subcomponents of working memory differentially contribute to performance on letter fluency and category fluency tasks. College students (N = 96) performed each type of verbal fluency task in isolation and concurrently with I of 3 secondary tasks. The secondary tasks were chosen for their putative involvement in different working memory subcomponents. Two subsystems of working memory, the phonological loop and the visuospatial sketchpad, were identified as important contributors to fluency performance, especially to performance on letter fluency and category fluency tasks, respectively. Moreover, the results also suggest that the executive function, mental set shifting, may be deployed to perform both letter fluency and category fluency tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)