China established a large-scale financial aid system in the late 1980s. This multilayered aid system aimed at enhancing educational and employment opportunities. However, very few studies have examined the impact of student aid on learning effort and outcome, career decisions, and early labor market performance. Using two recent Chinese college student surveys, this study found that students who received financial aid were significantly more likely to take more courses, spend more hours studying outside class, have a higher class ranking, and be less likely to fail a course. Additionally, having financial aid could promote graduate school enrollment and initial employment but had no significant impact on expected salary. Current aid programs for those who receive public financial assistance are thus beneficial in terms of educational outcome and employment perspective.
Atmospheric emissions of gas and particulate matter from a large ocean-going container vessel were sampled as it slowed and switched from high-sulfur to low-sulfur fuel as it transited into regulated coastal waters of California. Reduction in emission factors (EFs) of sulfur dioxide (SO2), particulate matter, particulate sulfate and cloud condensation nuclei were substantial (>= 90%). EFs for particulate organic matter decreased by 70%. Black carbon (BC) EFs were reduced by 41%. When the measured emission reductions, brought about by compliance with the California fuel quality regulation and participation in the vessel speed reduction (VSR) program, are placed in a broader context, warming from reductions in the indirect effect of SO4 would dominate any radiative changes due to the emissions changes. Within regulated waters absolute emission reductions exceed 88% for almost all measured gas and particle phase species. The analysis presented provides direct estimations of the emissions reductions that can be realized by California fuel quality regulation and VSR program, in addition to providing new information relevant to potential health and climate impact of reduced fuel sulfur content, fuel quality and vessel speed reductions.
Improvement of the AlGaN/GaN high-electron mobility transistor's (HEMT's) OFF-state breakdown voltage is achieved by implanting (19)F(+) ions at an energy of 50 keV and dose of 1 x 10(12) cm(-2) under the gate region using BF(3) as the source. The charge state of the implanted fluorine ions changes from positive to negative in the AlGaN/GaN structure because of fluorine's strong electronegativity. The negative-charged fluorine ions at the back side of the two-dimensional electron gas can raise the energy barrier of the GaN buffer layer under the channel, effectively blocking the current injected from the source to the high-field region of the GaN channel when the HEMT is biased at OFF-state. The source-injected electrons, if not blocked, could flow to the high-field region and initiate a premature three-terminal OFF-state breakdown in a conventional AlGaN/GaN HEMT. A 38% improvement of the three-terminal OFF-state breakdown voltage and 40% improvement of the power figure-of-merit V(BD-off)(2)/R(on) are achieved in the enhanced back barrier HEMT.
China operated an urbanization policy by which counties could be given city status between 1983 and 1997. The policy had substantial impacts on the new administrative entities, including more discretionary power and fiscal independence. Such "county-to-city upgrading" provided the central government with an instrument to reward localities. Using a large dataset covering all counties during 1993-1997. I show that upgrading is not an automatic procedure that endorses the high urbanization levels in existing counties. Although official guidelines for upgrading counties to cities were published, these requirements were largely ignored in practice. Instead, economic growth rate was the key factor in determining which counties obtained city status. This paper interprets the creation of county-level cities through upgrading as part of the incentive structure of Chinese local officials. The importance of both fiscal and political incentives facing the local government in promoting economic growth is highlighted.
At a rural site in the central Pearl River Delta (PRD) region in south China, fine particle (PM2.5) samples were collected during fall-winter 2007 to measure biogenic secondary organic aerosol (SOA) tracers, including isoprene SOA tracers (3-methyl-2,3,4-trihydroxy-1-butene, 2-methylglyceric acid, 2-methylthreitol and 2-methylerythritol), α-pinene SOA tracers (cis-pinonic acid, pinic acid, 3-methyl-1,2,3-butanetricarboxylic acid, 3-hydroxyglutaric acid and 3-hydroxy-4,4-dimethylglutaric acid) and a sesquiterpene SOA tracer (β-caryophyllinic acid). The isoprene-, α-pinene- and sesquiterpene-SOA tracers averaged 30.8±15.9, 6.61±4.39, and 0.54±0.56ngm−3, respectively; and 2-methyltetrols (sum of 2-methylthreitol and 2-methylerythritol, 27.6±15.1ngm−3) and cis-pinonic acid (3.60±3.76ngm−3) were the dominant isoprene- and α-pinene-SOA tracers, respectively. 2-Methyltetrols exhibited significantly positive correlations (p<0.05) with ambient temperature, probably resulting from the enhanced isoprene emission strength and tracer formation rate under higher temperature. The significantly positive correlation (p<0.05) between 2-methyltetrols and the estimated aerosol acidity with a slope of 59.4±13.4ngm−3 per μmol [H+] m−3 reflected the enhancement of isoprene SOA formation by aerosol acidity, and acid-catalyzed heterogeneous reaction was probably the major formation pathway for 2-methyltetrols in the PRD region. 2-Methylglyceric acid showed poor correlations with both temperature and aerosol acidity. The α-pinene SOA tracers showed poor correlations with temperature, probably due to the counteraction between temperature effects on the precursor emission/tracer formation and gas/particle partitioning. Among the α-pinene SOA tracers, only cis-pinonic acid and pinic acid exhibited significant correlations with aerosol acidity with slopes of −11.7±3.7 and −2.2±0.8ngm−3 per μmol [H+] m−3, respectively. The negative correlations observed for α-pinene SOA tracers might result from their transfer from particle to gas phase with the increase of aerosol acidity. The ratio of cis-pinonic acid plus pinic acid to 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA) ranged from 0.28 to 28.9 with a mean of 7.19, indicating the relatively fresh α-pinene SOA tracers during our campaign.