Rural Population Aging and the Hospital Utilization in Cities: The Rise of Medical Tourism in China.

The disparity of rural and urban hospital utilization has aroused much concern. With the improvement of their living standards, patients in rural areas have an emerging need for traveling across borders for better medical treatment in China. This paper reveals the medical tourism of rural residents towards urban hospitals driven by hospital needs and points out that such disparities may be caused by medical tourism. The ratio of people aged 65 and above in total rural populations was used to identify the potential target customers for medical tourism. Based on rural and urban datasets ranging from 2007-2017 on the provincial level, this paper presents a mobile treatment model and market concentration model with an ecological foundation. The feasible generalized least squared approach was used in the estimation of the fixed-effect regressions. The study found that there was a positive and significant relationship between rural old-age ratios and urban inpatient visits from different income groups. On average, a one percent rise in rural old-age ratio would increase the inpatient visits of urban hospitals by 138 thousand persons. There was also a positive and significant relationship between the rural old-age ratio and the market concentration of urban inpatient visits. It was found that the rural old-age ratio significantly influenced the market concentration of urban inpatient visits in the middle-high income regions. The research showed that each income group from the rural aged population had participated in medical tourism, traveled to urbanized regions and made inpatient visits to urbanized medical facilities. It was also indicated that the rural aged population, especially from the middle-high income groups had a positive and significant influence on the market concentration of urban inpatient visits in the province.

Individual and bivalent vaccines against botulinum neurotoxin serotypes A and B using DNA-based Semliki Forest virus vectors.

We evaluated individual and bivalent replicon vaccines against Clostridiumbotulinum neurotoxin serotypes A (BoNT/A) or B (BoNT/B). The DNA replicon vaccine (pSCARSBHc) encoding the Hc domain of BoNT/B (BHc) induced better responses and protection against BoNT/B mouse challenge than conventional DNA vaccine. The dual-expressing DNA vaccine (pSCARSA/BHc) protected similarly to a DNA replicon vaccine mixture (pSCARSAHc+pSCARSBHc). Additionally, recombinant SFV particles, VRP-AHc or VRP-BHc, protected mice from high-dose BoNT/A or BoNT/B challenge, respectively. Mice given either dual-expressing VRP-A/BHc or mixture of VRP-AHc and VRP-BHc were protected from challenge with serotype A/B mixtures. These data justify further testing in other animals or humans.

[Short-term monitoring of methane emission regulation from a municipal solid waste landfill].

To understand the regulation and influencing factors of methane emission from landfills in China, rates of methane emission from Hangzhou Tianziling municipal solid waste landfill were measured by static chamber technique. The emission rates ranged from 3.67 to 36.65 mmol x (m2 x h)(-1) on average of the two tested points (No. 1 and No. 2) during 24-hour cycle. The max ratio of emission rates between the two tested points was 625. The difference with the rates of the two tested points could be explained by the depth of the cover soils. Rate of methane emission from each point correlated with atmospheric pressure and water content of landfill cover soils, and the result from stepwise regression was r2 = 0.89 for point No. 1, r2 = 0.76 for point No. 2. Rates of methane emission varied from -0.23 to 0.32 mmol (m2 x h)(-1) on average in 40-day test (points with same depth of cover soils). The low correlation (r2 = 0.15) with atmospheric pressure showed that atmospheric pressure was not the decisive factor. For some time, emission rates correlated with water content or temperature of the landfill cover soils significantly, but not obvious (r2 < 0.4) during the whole monitoring time. When atmospheric pressure was included, the results of stepwise regression were improved significantly, which showed that methane emission rates were influenced by different factors, but the effect of each factor was not the same at a different time.

In situ distributions and characteristics of heavy metals in full-scale landfill layers.

The leachate from methanogenic landfill normally contains low concentrations of heavy metals. Little samples had ever been collected from the full-scale landfill piles owing to technical difficulty for well drilling. We drilled two wells in Hangzhou Tianziling landfill, 20 m and 32 m in depth each, and collected solid samples of waste age of 1-4 years from both wells. The total amounts, the sequentially extracted amounts, and the chemical binding forms of heavy metals of the samples collected at different depths were measured. With the correlation between leachate production amount and the yearly rainfall amount, the leached ratio of the heavy metals were estimated only 0.13%, 1.8%, 0.15%, and 0.19% of Cu, Cd, Pb, and Zn, respectively. The heavy metals amounts in the main compositions of MSW, like glass, food waste, paper, coal cinders, were measured using fresh MSW samples. Afterward, the contents of heavy metals initially landfilled were estimated. A positive correlation was noted between the measured and the estimated initial contents of heavy metals, indicating that the low migration of heavy metals in landfill layers. However, among the metals investigated, Zn has shown better mobility inside landfill layers. Acid volatile sulfide (AVS) and the simultaneously extracted metals (SEM) were measured for all collected samples with optimal reaction conditions identified to yield nearly perfect sulfide recovery as follows: 100 g wet samples, 80 mL min(-1) N(2) flow rate, reaction time of 150 min. The SEM/AVS ratios ranged 25-45, indicating that the AVS was insufficient to immobilize the SEM. Sequential extraction using six-fraction scheme revealed that the sum of exchangeable and the avid soluble fractions of heavy metals follow: Zn>Cd>Cu, Ni, Pb>Cr. The insoluble fraction of heavy metals in MSW was high, for instance, over 80% for Cr and Pb high insoluble fractions of heavy metals in the landfilled MSW and the sorption capability of the methanogenic landfill layers should be responsible to the low concentrations of heavy metals found in leachate.

Microbiological indication of municipal solid waste landfill non-stabilization.

Accidental collapse resulted from unstable factors is an important technological problem to be solved in sanitary landfill. Microbiological degradation of organic matters in landfilled solid waste are an important unstable factor. A landfill reactor was thus manufactured and installed to examine quantitative and population dynamics of microorganisms during degradation of landfilled solid waste. It was showed that unstable landfill can be reflected and indicated by microbiological features such as rapidly decreased growth amount of microorganisms, no detection of fungi and actinomyces, and changing the dominant population into methanogenic bacteria and Acinotobacter.

A risk factor analysis of municipal domestic refuse landfills using a reactor with high water input.

Collapse, explosion and water pollution by leachate have been three major problems in confining the development of sanitary landfilling technology as an economical method for disposal of municipal refuse. Potential risk factors including settlement of landfilled refuse, the generation of methane, carbon dioxide and other gases from landfill, the dynamic changes in temperature within the landfill and its ambient environment, as well as COD(Cr), BOD5, nutrients (TKN, TP and organic matter), heavy metals (Cu, Pb and Zn) and pH in landfill leachate were simulated using a reactor with high water input. It was indicated that high content of organic components in landfilled refuse is a key risk factor to cause abrupt collapse and accidental explosion in the landfill because they have impact not only on the settlement, but also on the release of methane and other gases. Elevated temperatures coincided with maximum generation of methane and other gases, thus increasing the risk of accidental explosion. Leachate quality was closely related with the release of COD(Cr) and BOD5 and heavy metals such as Cu, Pb and Zn, as well as organic pollutants, there was less release of TKN and TP. The mass balance analysis for the reactor showed that 36% of organic carbon reduction in the refuse during the simulations was discharged into leachate as soluble organic carbon, and 3% was converted to methane and carbon dioxide as gas production. Mixing of refuse with soil and sand particles, the so-called drill-a-hole method and recycling leachate were measures suggested in order to mitigate and avoid potential accidents.