Fast optical channel recovery in field demonstration of 100-Gbit/s Ethernet over OTN using real-time DSP.

A field trial of 100-Gbit/s Ethernet over an optical transport network (OTN) is conducted using a real-time digital coherent signal processor. Error free operation with the Q-margin of 3.2 dB is confirmed at a 100 Gbit/s Ethernet analyzer by concatenating a low-density parity-check code with a OTN framer forward error correction, after 80-ch WDM transmission through 6 spans x 70 km of dispersion shifted fiber without inline-dispersion compensation. Also, the recovery time of 12 msec is observed in an optical route switching experiment, which is achieved through fast chromatic dispersion estimation functionality.

Relative efficiency of radiation sources for photopolymerization.

The aim of this study was to evaluate the characteristics of new-generation light-emitting diode (LED) units in comparison with the conventional tungsten-halogen, plasma arc, and first-generation LED units reported in our previous study. The irradiance of light from new-generation LED units, the temperature rise of the bovine enamel surface, and the depth of cure of composites exposed to each unit were investigated. The irradiances in the range 400-515 nm emitted from the new-generation LED units were greater than those from the first-generation LED units. The temperature increase was 15-25 degrees C for new-generation LED units compared with a typical value of 5 degrees C for the first-generation LED units at 10 s of irradiation. The relationship between the depth of cure and the logarithm of total exposure energy suggested that LED units can cure light-cured composite resins more efficiently than tungsten-halogen or plasma arc units.

[Results of chemotherapy using new anti-cancer drugs since S-1 for advanced or recurrent gastric cancer in our institute].

In many medical institutes the treatment for advanced (not resectable or radical grade C) or recurrent gastric cancer seems to be based on a regional perspective or prognostic restriction, and rarely on large-scale clinical studies; instead the selection is based on effective cases reported in the literature or on own.s own. In the current situation, chemotherapy using new anti-cancer drugs since S-1 has actually appeared to improve the prognosis or to maintain better QOL. We examined 46 cases (28 advanced (not resectable or radical grade C) cases and 18 recurrent cases after curative operation) during the period from January 2001 to December 2005. In 27 chemotherapy cases (1-year survival 52.5%, 2-year survival 31.5%, 3-year survival 19.5%, and MST=344 day), the survival time was significantly extended compared to 19 cases without chemotherapy (1-year survival 10.5% and MST=102 day) (p<0.0001). In the 27 chemotherapy cases, between 5 performance status (PS) 0 cases and 8 PS 1 cases, there was no significant difference in survival. But in 12 PS 2 cases, survival was significantly shorter smaller than that of PS 0 or PS 1 cases (p<0.05, p<0.001). Also, the period in the hospital during survival time of 6 cases, 2-year survival or more, was significantly shorter than that of 10 less than 1-year survival cases treated with chemotherapy. These findings led us to conclude that chemotherapy using new anti-cancer drug since S-1 showed excellent QOL in addition to longer survival benefits at the present time, when a standard treatment for to advanced or recurrent gastric cancer has not yet been established. It seemed that prognostic improvement by maintaining further excellent QOL could be expected if standard treatments based on the results of large-scale clinical studies were established.

Relationship between water status in dentin and interfacial morphology in all-in-one adhesives.

OBJECTIVES: All-in-one adhesive systems have been recently developed to simplify bonding procedures. The adhesives containing acidic resin monomers generate a relatively thin bonding zone between dentin and composite. This zone may be left acidic and permeable when polymerization is poor. In this study, the effect of water contained in dentin on the quality of the bonding interface was morphologically investigated for all-in-one adhesives. METHODS: Intact coronal dentin (hydrated dentin), desiccated coronal dentin (dehydrated dentin), caries-affected dentin (CAD) and resin composites were used for adherends to assess the effects of water contained in dentin on the ultra-structures of bonding interfaces created with two all-in-one adhesives and a resin composite. RESULTS: The bonding interfaces were observed under TEM without demineralization. Voids of various sizes were found at the bottom of the adhesive resin layers along the bonding interface of hydrated dentin, while dehydrated dentin, CAD and resin composites did not generate voids. The results showed that the voids were possibly formed by water that had penetrated from the underlying dentin. CONCLUSION: When the adherend contains little water, the formation of voids will not occur. It was verified that a phenomenon of void formation would not occur in a clinical situation in which caries-affected dentin is mainly subjected to adhesive practices.

Light exposure required for optimum conversion of light activated resin systems.

OBJECTIVE: The aim of this study was to evaluate the relationship between the degree of conversion (DC) of composites and the light intensity using LED-curing units and also to determine the amount of exposure required to achieve optimal curing. METHOD: The light outputs of light-curing units and the depths of cure of composites exposed to these units were determined using the methods outlined in modified ISO standards, ISO/TS10650 and ISO 4049, respectively. The distributions of DC in composites were investigated by IR spectra of microareas obtained at various depths from the irradiated surface of thin specimens cut out from the cured composites. IR spectra were measured using a Fourier transform infrared spectrometer equipped with a microscopic unit. DC was calculated from the changes in the amount of C=C double bonds in the IR spectra. RESULTS: The light intensity at various depths through the cured composite was calculated from the attenuation coefficient of each material, obtained from the linear relationship between the depth of cure and the logarithm of the amount of exposure, which is defined as the product of the irradiance and irradiation time. There was a third or fourth order regression relationship between DC and the logarithm of total light energy at a particular depth. SIGNIFICANCE: The minimum light energy required to produce a saturated DC was about 1000 s mW/cm2.

Effect of mixing method on the porosity of encapsulated glass ionomer cement.

OBJECTIVE: To observe cement specimens mixed by various methods non-destructively using microfocus computerized tomography (micro-CT) and to evaluate the effect of mixing method on porosity. METHOD: Five glass ionomer cements were used: two were hand-mixed and three were encapsulated. The latter were mixed either by shaking or rotating. Fifteen cylindrical specimens were prepared for each material by each mixing method and stored in distilled water at 37 degrees C until testing. The specimens were observed and analyzed using micro-CT. 201 sliced images were obtained horizontally along the length of the specimens. Three-dimensional reconstructions were made and the sizes, numbers and total volume ratio of bubbles in the specimens were calculated. RESULTS: Mixing method had a significant effect on porosity (P<0.05). For the luting/lining cement, mechanical mixing produced a significantly higher porosity (P<0.05). For the restorative cement, there were only small differences in porosity between specimens mixed by the two methods. More large bubbles were detected in specimens mixed mechanically than by hand for the fluid material. This suggested that for low-viscosity materials bubbles may combine until a certain viscosity is reached during setting. SIGNIFICANCE: The strength of glass ionomer cement is affected by incorporated porosity and this depends on the mixing method. For low-viscosity cements, hand-mixing is favored in order to reduce porosity and increase strength, but this is not generally applicable to high-viscosity cements.

Effect of aperture size on irradiance of LED curing units.

OBJECTIVE: The aim of this study was to evaluate the light output from LED-curing units measured according to the current ISO standards. The effect of aperture size on irradiance was also evaluated. METHOD: The irradiance of light-curing units and the depths of cure of composites exposed to these units were determined using the methods outlined in ISO standards, ISO/TS10650 and ISO 4049, respectively. The irradiance measured through two different sized apertures was also measured. RESULTS: The irradiance measured with an aperture was greater than that without an aperture. For each light-curing unit and material, there was a linear relationship between the depth of cure and the logarithm of the amount of exposure, which is defined as the product of the irradiance and irradiation time. The correlation coefficients of these linear relationships, using data obtained from the different units was only moderate when the irradiance was measured without an aperture. The correlations improved with decreasing aperture size. SIGNIFICANCE: Since the irradiance is affected by the angular aperture of the light guide and the size of the mold for measuring depth of cure of resin in ISO 4049 is 4-mm diameter, the irradiance through a 4-mm aperture should be used in the determination of the relationship between depth of cure and light exposure.

Comparison of halogen, plasma and LED curing units.

This study evaluated the characteristics of two kinds of recently developed light-curing unit; plasma arc and blue light emitting diodes (LED), in comparison with a conventional tungsten-halogen light-curing unit. The light intensity and spectral distribution of light from these light-curing units, the temperature rise of the bovine enamel surface and the depth of cure of composites exposed to each unit were investigated. The light intensity and depth of cure were determined according to ISO standards. The spectral distributions of emitted light were measured using a spectro-radiometer. The temperature increase induced by irradiation was measured by using a thermocouple. Generally, light intensities in the range 400-515 nm emitted from the plasma arc were greater than those from other types. Light in the UV-A region was emitted from some plasma arc units. The required irradiation times were six to nine seconds for the plasma arc units and 40 to 60 seconds for the LED units to create a depth of cure equal to that produced by the tungsten-halogen light with 20 seconds of irradiation. The temperature increased by increasing the irradiation time for every light-curing unit. The temperature increases were 15 degrees C to 60 degrees C for plasma arc units, around 15 degrees C for a conventional halogen unit and under 10 degrees C for LED units. Both the plasma arc and LED units required longer irradiation times than those recommended by their respective manufacturers. Clinicians should be aware of potential thermal rise and UV-A hazard when using plasma arc units.

Application of thermography in dentistry--visualization of temperature distribution on oral tissues.

The purpose of this study was to devise and propose appropriate conditions for the photographing of thermal images in the oral cavity and to evaluate which thermography techniques can be applied to dentistry by evaluating the differences in temperature among oral tissues. Thermal images of oral cavities of 20 volunteers in normal oral condition were taken according to the guidelines of the Japanese Society of Thermography, with five added items for oral observation. The use of a mirror made it possible to take thermal images of the posterior portion or palate. Teeth, free gingiva, attached gingiva and alveolar mucosa were identified on thermal images. There were differences in temperature between teeth, free gingiva, attached gingiva and alveolar mucosa. These were nearly in agreement with the anatomical view. Thermography need no longer be restricted to the anterior portion using a mirror, and can now be applied to the dental region.

Diffusion coefficient of water through dental composite resin.

Water sorption of polymer filling materials affects dimensional stability, mechanical properties and bonding strength with tooth structures. To clarify the effect of the degradation on service life and micro-leakage, the diffusion coefficient of water through the resin should be identified. Distributions of time-dependent water concentrations in the resin were computed. Water sorption of composite resin discs with different thicknesses was measured and compared with the solution of Fick's second law. The diffusion coefficient of water through the resin discs was computed to be D=3.9-5.0 x 10(-13)m(2)/s from the measurements of specimens with different thicknesses. Results of water sorption measurements for the discs with different thicknesses were in good agreement with the theoretical results. The relationship among the thickness of the disc, the diffusion coefficient and the water sorption ratio was shown clearly. The testing method for water sorption by International Standard ISO 4049 for resin-based filling materials was discussed.