No abstract

Hepatitis A, the predominant reported etiologic form of viral hepatitis in Taiwan, continues to be a disease primarily of children and young adults. A seroepidemiologic study was performed to assess the seroprevalence of hepatitis A (HAV) antibodies in the southern Taiwan general population in 1998 and is compared with results of a similar study in 1992. A total of 948 subjects (477 male and 471 female) with ages ranging from 0.3 to 63 years were stratified into 14 age-specific groups. The presence of anti-HAV antibodies was detected using a commercially available radioimmunoassay. Fifteen percent of the subjects were positive for anti-HAV antibodies, which is lower than that in 1992 (P < 0.001). Seroprevalences were 14.1% for males and 22.6% for females (P = 0.006). The pattern of anti-HAV seroprevalence was distinguishable from that found in 1992; minimum seroconversion occurred at ages ranging from 1 to 30 years. Prevalence of seropositive subjects decreased markedly for the < 1, 13-15, 16-19, 20-24, 25-29, and 30-39 year age groups in comparing 1998 with 1992. The current study demonstrates a continuing decline in the prevalence of HAV among children, adolescents, and young adults. The findings can be ascribed to the improvement of socioeconomic status and modernization of environmental sanitation. As a consequence of this changing trend of endemicity and the resulting lack hepatitis A antibodies among the general population in Taiwan, the risk of sudden major outbreaks is increased because of increasing international travel and immigration, particularly during and after natural disasters. HAV vaccination will be important for the prevention and control of HAV outbreaks in the community.

Dynamic optical networking has promising potential to support the rapidly changing traffic demands in metro and long-haul networks. However, the improvement in dynamicity is hindered by wavelength-dependent power excursions in gain-controlled erbium doped fiber amplifiers (EDFA) when channels change rapidly. We introduce a general approach that leverages machine learning (ML) to characterize and mitigate the power excursions of EDFA systems with different equipment and scales. An ML engine is developed and experimentally validated to show accurate predictions of the power dynamics in cascaded EDFAs. Recommended channel provisioning based on the ML predictions achieves within 1% error of the lowest possible power excursion over 94% of the time. We also showcase significant mitigation of EDFA power excursions in super-channel provisioning when compared to the first-fit wavelength assignment algorithm.

No abstract

Abstract:We grafted thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) brushes from monodisperse SiO 2 microspheres through surface-initiated atom transfer radical polymerization (SI ATRP) to generate core-shell structured SiO 2 @PNIPAM microspheres (SPMs). Regular-sized SPMs dispersed in aqueous solution and packed as photonic crystals (PCs) in dry state. Because of the microscale of the SPMs, the packing behavior of the PCs in water can be observed by optical microscopy. By increasing the temperature above the lower critical solution temperature (LCST) of PNIPAM, the reversible swelling and shrinking of the PNIPAM shell resulted in dispersion and precipitation (three-dimensional aggregation) of the SPM in aqueous solution. The SPMs were microdispersed in a water layer to accommodate the aggregation along two dimensions. In the microdispersion, the SPMs are packed as PCs with microscale spacing between SPMs below the LCST. When the temperature is increased above the LCST, the microdispersed PCs exhibited a close-packed arrangement along two dimensions with decreased spacing between SPMs. The change in spacing with increasing temperature above the LCST resulted in a color change from red to blue, which could be observed by the naked eye at an incident angle. Thus, the SPM array could be applied as a visual temperature sensor.

No abstract

A novel PCL-b-PnBA-b-PMMA was designed and applied to construct ordered nanostructures within epoxy thermosets.

We propose and analyze a scalable microring-based Clos switch fabric architecture constructed with switch-and-select switching stages. A silicon 4 × 4 building block that was designed and fabricated through American Institute for Manufacturing Integrated Photonics is used for the proof-of-principle demonstration of a 16 × 16 Clos switch fabric. By fully blocking the first-order crosstalk, the 4 × 4 device is measured to show a crosstalk ratio in the range of-57 to-48.5 dB, enabling better than-39 dB crosstalk for the 16 × 16 switch. Our study shows that the three-stage Clos design enables up to a factor of 4 in the reduction of the number of switching cells compared to single-stage switch-and-select fabrics. We further explore the design space for both first-order and secondorder switching elements using the foundry-validated parameters and how these factors impact the performance and scalability of the three-stage Clos switch. A detailed power penalty map is drawn for Clos switch fabrics with various scales, which reveals that the ultimate key limiting factor is the shuffle insertion loss. An optimized 32-port Clos switch fabric using foundry-enabled parameters is shown to have a less than 10-dB power penalty.