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Single-nanowire solar cells (SNSCs) have attracted considerable attention due to their unique light-harvesting capability mediated by the optical antenna effect and the high photoconversion efficiency due to the orthogonalization of the carrier collection to the photon incidence. We present a detailed prediction of the light-conversion efficiency of Si SNSCs based on finite-element simulation and thermodynamic balance analysis, with especially focusing on the comparison between SNSCs and film systems. Carrier losses due to radiative and Auger recombinations are introduced in the analysis of the limiting efficiency, which show that the Auger recombination plays a key role in accurately predicting the efficiency of Si SNSCs, otherwise, the device performance would be strongly overestimated. The study paves a more realistic way to evaluate the nanostructured solar cells based on indirect-band photoactive materials. [ABSTRACT FROM AUTHOR]

Surface plasmons can squeeze light into a deep-subwavelength space and generate abundant hot electrons in the nearby metallic regions, enabling a new paradigm of photoconversion by the way of hot electron collection. Unlike the visible spectral range concerned in previous literatures, we focus on the communication band and design the infrared hot-electron photodetectors with plasmonic metal-insulator-metal configuration by using full-wave finite-element method. Titanium dioxide-silver Schottky interface is employed to boost the low-energy infrared photodetection. The photodetection sensitivity is strongly improved by enhancing the plasmonic excitation from a rationally engineered metallic grating, which enables a strong unidirectional photocurrent. With a five-step electrical simulation, the optimized device exhibits an unbiased responsivity of ~0.1 mA/W and an ultra-narrow response band (FWHM = 4.66 meV), which promises to be a candidate as the compact photodetector operating in communication band. [ABSTRACT FROM AUTHOR]

Background: The disparity between government health expenditures across regions is more severe in developing countries than it is in developed countries. The capitation subsidy method has been proven effective in developed countries in reducing this disparity, but it has not been tested in China, the world's largest developing country.Methods: The convergence method of neoclassical economics was adopted to test the convergence of China's regional government health expenditure. Data were obtained from Provinces, Prefectures and Counties Fiscal Statistical Yearbook (2003-2007) edited by the Chinese Ministry of Finance, and published by the Chinese Finance & Economics Publishing House.Results: The existence of σ-convergence and long-term and short-term β-convergence indicated the effectiveness of the capitation subsidy method in the New Rural Cooperative Medical Scheme on narrowing county government health expenditure disparities. The supply-side variables contributed the most to the county government health expenditure convergence, and factors contributing to convergence of county government health expenditures per capita were different in three regions.Conclusion: The narrowing disparity between county government health expenditures across regions supports the effectiveness of the capitation subsidy method adopted by China's New Rural Cooperative Scheme. However, subsidy policy still requires further improvement. [ABSTRACT FROM AUTHOR]

The article presents a study on limiting efficiencies of silicon hydride-based single-nanowire solar cells under single and tandem junction configurations. Topics discussed include role of semiconductor nanowires in manufacturing efficient photovoltaic devices, strategy to improve the efficiency of SCs, and use of general thermodynamic principle for balance analysis.

Objective: Reform of the health care system in urban areas of China has prompted concerns about the utilization of Community Health Centers (CHC). This study examined which of the dominant primary care delivery models, i.e., the public CHC model, the 'gate-keeper' CHC model, or the hospital-owned CHC models, was most effective in enhancing access to and quality of care for patients with chronic illness. Methods: The case-comparison design was used to study nine health care organizations in Guangzhou, Dongguan, and Shenzhen cities within Guangdong province, China. 560 patients aged 50 or over with hypertension or diabetes who visited either CHCs or hospitals in these three cities were surveyed by using face-to-face interviews. Bivariate analyses were performed to compare quality and value of care indicators among subjects from the three cities. Multivariate analyses were used to assess the association between type of primary care delivery and quality as well as value of chronic care after controlling for patients' demographic and health status characteristics. Results: Patients from all three cities chose their current health care providers primarily out of concern for quality of care (both provider expertise and adequate medical equipment), patient-centered care, and insurance plan requirement. Compared with patients from Guangzhou, those from Dongguan performed significantly better on most quality and value of care indicators. Most of these indicators remained significantly better even after controlling for patients' demographic and health status characteristics. The Shenzhen model (hospital-owned and -managed CHC) was generally effective in enhancing accessibility and continuity. However, coordination suffered due to seemingly duplicating primary care outpatients at the hospital setting. Significant associations between types of health care facilities and quality of care were also observed such that patients from CHCs were more likely to be satisfied with traveling time and follow-up care by their providers. Conclusion: The study suggested that the Dongguan model (based on insurance mandate and using family practice physicians as 'gate-keepers') seemed to work best in terms of improving access and quality for patients with chronic conditions. The study suggested adequately funded and well-organized primary care system can play a gatekeeping role and has the potential to provide a reasonable level of care to patients. [ABSTRACT FROM AUTHOR]

Background: China had 236 million internal migrants in 2012 and the majority of them migrated from rural to urban areas. The research based on medical and epidemical records found that the migrants had worse health than the urban residents, but the household and working place investigations reported better health status. The sick or unhealthy migrants are likely to return to their hometowns, which in turn may cause a report bias or over-estimation of the health status of rural-to-urban migrants in China. This paper explores the association of migration status and the physical and psychological health of Chinese internal migrants. Methods: Nationally representative household survey data from the China Labor-force Dynamics Survey 2012 (CLDS) were used to analyze the association between the migration status and the health status of internal migrants in China. Migration status of the respondents was measured by hukou status and migration experience and all respondents were divided into four groups: returned population, migrant population, urban residents, and rural residents. Health status of respondents was measured by self-reported physical and psychological health. Results: Migration experience was associated with the physical health of the returned population. The physical health of the returned population was worse than the migrant population and was distinguished by age and sex. The physical health status of migrant population was significantly better than rural residents, but not significantly better than urban residents. However, the association between migration status and psychological health was not statistically significant. Besides migration status, the socioeconomic status (SES) had a positive correlation with both physical and psychological health status, while occupational hazards exerted negative influence. Conclusion: The results indicate a tight association between migration experience and health status. The internal unhealthy migrants were more likely to return to their hometown and the migrant population might have limited health advantage. [ABSTRACT FROM AUTHOR]

Single-nanowire photodetectors (SNPDs) are mostly propelled by p-n junctions, where the detection wavelength is constrained by the band-gap width. Here, we present a simple doping-free metal/semiconductor/metal SNPD, which shows strong detection tunability without such a material constraint. The proposed hot-electron SNPD exhibits superior optical and electrical advantages, i.e., optically the coaxial design leads to a strong asymmetrical photoabsorption and results in a high unidirectional photocurrent, as desired by the hot-electron collection; electrically the hot-electrons are generated in the region very close to the barrier, facilitating the electrical transport. Rigorous calculations predict an unbiased photoresponsivity of ~200 nA/mW. [ABSTRACT FROM AUTHOR]

A numerical investigation on the third-order nonlinear optical properties of a plasmonic system composed by metal film-coupled nanowires is reported. The linear and nonlinear optical characteristics are studied by finite-difference time-domain (FDTD) method. To substantially improve the nonlinear effect, the geometric parameters of the system are carefully engineered to excite strong plasmon gap resonance with dramatically enhanced electric field intensity at the gap between the nanowires and the film. The third-harmonic generation (THG) property is examined by nonlinear FDTD simulation. It shows that the THG efficiency estimated from the nonlinear optical absorption can be ~1X10-5 under an incident power density of 5.2GW/cm². Plasmonic resonance is necessary to achieve highly efficient THG since the system on resonance shows the THG intensity 4 orders of magnitude higher than that of an off-resonance system. [ABSTRACT FROM AUTHOR]

A continuously tunable multi-wavelength polymer laser based on a triangular-lattice photonic crystal cavity is demonstrated. The triangular-lattice resonator was initially fabricated through multiple interference exposure and was then replicated into a low refractive index polymer via UV-nanoimprinting. The blend of a blue-emitting conjugated polymer and a red-emitting one was used as the gain medium. Three periods in the scalene triangular-lattice structure yield stable tri-wavelength laser emission (625.5 nm, 617.4 nm and 614.3 nm) in six different directions. A uniformly aligned liquid crystal (LC) layer was incorporated into the cavity as the top cladding layer. Upon heating, the orientation of LC molecules and thus the effective refractive index of the lasing mode changes which continuously shifts the lasing wavelength. A maximum tuning range of 12.2 nm was observed for the lasing mode at 625.5 nm. This tunable tri-wavelength polymer laser is simple constructed and cost-effective. It may find application in the fields of biosensors and photonic integrated circuits. [ABSTRACT FROM AUTHOR]