TRANSITION AND REFORM OF CHINA'S AGRICULTURAL SYSTEM TOWARD A MARKET-ORIENTED ECONOMY: LESSONS FROM THE TAIWAN EXPERIENCE

As China proceeds through the process of economic development to an industrialized economy, its agriculture will undergo substantial stress and structural change. China may be able to effectively utilize the experiences of Taiwan agriculture and its policies in adjusting to change. These policies and their impacts are explained in this working paper.Agricultural and Food Policy,

Physical Layer Security in Wireless Ad Hoc Networks Under A Hybrid Full-/Half-Duplex Receiver Deployment Strategy

This paper studies physical layer security in a wireless ad hoc network with numerous legitimate transmitter-receiver pairs and eavesdroppers. A hybrid full-/half-duplex receiver deployment strategy is proposed to secure legitimate transmissions, by letting a fraction of legitimate receivers work in the full-duplex (FD) mode sending jamming signals to confuse eavesdroppers upon their information receptions, and letting the other receivers work in the half-duplex mode just receiving their desired signals. The objective of this paper is to choose properly the fraction of FD receivers for achieving the optimal network security performance. Both accurate expressions and tractable approximations for the connection outage probability and the secrecy outage probability of an arbitrary legitimate link are derived, based on which the area secure link number, network-wide secrecy throughput and network-wide secrecy energy efficiency are optimized respectively. Various insights into the optimal fraction are further developed and its closed-form expressions are also derived under perfect self-interference cancellation or in a dense network. It is concluded that the fraction of FD receivers triggers a non-trivial trade-off between reliability and secrecy, and the proposed strategy can significantly enhance the network security performance.Comment: Journal paper, double-column 12 pages, 9 figures, accepted by IEEE Transactions on Wireless Communications, 201

From Smoking to Cancers: Novel Targets to Neuronal Nicotinic Acetylcholine Receptors

Cigarette smoking bears a strong etiological association with many neovascularization-related diseases, including cancer, cardiovascular disease, and age-related macular degeneration. Cigarette smoke is a complex mixture of many compounds, including nicotine, which is the major active and addictive component of tobacco. Nicotine and its specific metabolized carcinogens directly bind to nicotinic acetylcholine receptors (nAChRs) on cell membranes and trigger the nAChR signal cascade. The nAChRs were originally thought to be ligand-gated ion channels that modulate physiological processes ranging from neurotransmission to cancer signaling. For several decades, the nAChRs served as a prototypic molecule for neurotransmitter receptors; however, they are now important therapeutic targets for various diseases, including Alzheimer's and Parkinson's diseases, schizophrenia, and even cancer. This paper describes recent advances in our understanding of the assembly, activity, and biological functions of nicotinic receptors, as well as developments in the therapeutic application of nicotinic receptor ligands

Mechanism of action and resistant profile of anti-HIV-1 coumarin derivatives

Dicamphanoyl khellactone (DCK) is a coumarin derivative that can potently inhibit HIV-1 replication. DCK does not inhibit RNA-dependent DNA synthesis. However, an HIV reverse transcriptase (RT) inhibitor-resistant strain, HIV-1/RTMDR1, is resistant to DCK. Thus, it is possible that HIV-1 RT is the target of DCK. To test this possibility, DCK-resistant viruses were selected in the presence of DCK. Our results indicate that a single amino acid mutation, E138K in HIV-1 RT, is sufficient to confer DCK resistance. Interestingly, a DCK derivative, 3'R,4'R-Di-O-(-)-camphanoyl-2-ethyl-2',2'-dimethyldihydropyrano[2,3-f]chromo ne (DCP8), is effective against HIV-1/RTMDR1. However, the DCK-escape virus carrying the E138K mutation remains resistant to DCP8. Since DCK did not inhibit the RNA-dependent DNA polymerase activity of HIV-1 RT when using poly-rA or poly-rC as template, we evaluated the effect of DCK on the DNA-dependent DNA polymerase activity of HIV-1 RT. Our results indicate that DCK can inhibit the DNA-dependent DNA polymerase activity of HIV-1 RT. In conclusion, DCK is a unique HIV-1 RT inhibitor that inhibits the DNA-dependent DNA polymerase activity. In contrast, DCK did not significantly affect the RNA-dependent DNA polymerase activity when poly-rA or poly-rC was used as templates. An E138K mutation in the non-nucleoside RT inhibitors (NNRTIs) binding pocket of HIV-1 RT confers resistance to DCK and its chromone derivative, DCP8

Understanding Mobile Apps Continuance Usage Behavior and Habit: An Expectance-Confirmation Theory

With the growing development of information technology and the wireless telecommunication network nowadays, mobile devices have been expanding rapidly and have been emerging as important tools for consumers. Using m-services and applications (apps) on mobile devices becomes custom in people’s daily lives. This study proposes a theoretical model to explore the continued usage behavior for smartphone. The objective of this study is to explore how perceived usefulness, perceived enjoyment, and confirmation influencing satisfaction and habit of consumers, and in turn influencing continued usage behavior, as well as the moderating effect of three characteristics of m-commerce. The proposed model will empirically be tested using survey method and collecting data from smartphone users in longitudinal setting. The structural equation modeling technique will be used to evaluate the causal model and confirmatory factor analysis will be performed to examine the reliability and validity of the measurement model. The findings of this study are expected to illustrate how factors influence individuals to use m-services and mobile apps and become a habit, as well as how these habits influence continued smartphone usage

Nearly isotropic upper critical fields in a SrFe1.85_{1.85}Co0.15_{0.15}As2_{2} single crystal

We study temperature dependent upper critical field $H_{\rm c2}$ of a SrFe$_{1.85}$Co$_{0.15}$As$_{2}$ single crystal (\textit{T$_c$}=20.2 K) along \textit{ab}-plane and \textit{c}-axis through resistivity measurements up to 50 T. For the both crystalline directions, $H_{\rm c2}$ becomes nearly isotropic at zero temperature limit, reaching $\sim$ 48 T. The temperature dependence of the $H_{\rm c2}$ curves is explained by interplay between orbital and Pauli limiting behaviors combined with the two band effects.Comment: Proceedings of M2S-IX, Tokyo 200

Long-term and seasonal changes in nutrients, phytoplankton biomass, and dissolved oxygen in deep bay, Hong Kong

Deep Bay is a semienclosed bay that receives sewage from Shenzhen, a fast-growing city in China. NH 4 is the main N component of the sewage (>50% of total N) in the inner bay, and a twofold increase in NH 4 and PO 4 concentrations is attributed to increased sewage loading over the 21-year period (1986-2006). During this time series, the maximum annual average NH 4 and PO 4 concentrations exceeded 500 and 39 μM, respectively. The inner bay (Stns DM1 and DM2) has a long residence time and very high nutrient loads and yet much lower phytoplankton biomass (chlorophyll (Chl) 2 mg L -1) than expected. Because it is shallow (̃2 m), phytoplankton growth is likely limited by light due to mixing and suspended sediments, as well as by ammonium toxicity, and biomass accumulation is reduced by grazing, which may reduce the occurrence of hypoxia. Since nutrients were not limiting in the inner bay, the significant long-term increase in Chl a (0. 52-0. 57 μg L -1 year -1) was attributed to climatic effects in which the significant increase in rainfall (11 mm year -1) decreased salinity, increased stratification, and improved water stability. The outer bay (DM3 to DM5) has a high flushing rate (0. 2 day -1), is deeper (3 to 5 m), and has summer stratification, yet there are few large algal blooms and hypoxic events since dilution by the Pearl River discharge in summer, and the invasion of coastal water in winter is likely greater than the phytoplankton growth rate. A significant long-term increase in NO 3 (0. 45-0. 94 μM year -1) occurred in the outer bay, but no increasing trend was observed for SiO 4 or PO 4, and these long-term trends in NO 3, PO 4, and SiO 4 in the outer bay agreed with those long-term trends in the Pearl River discharge. Dissolved inorganic nitrogen (DIN) has approximately doubled from 35-62 to 68-107 μM in the outer bay during the last two decades, and consequently DIN to PO 4 molar ratios have also increased over twofold since there was no change in PO 4. The rapid increase in salinity and DO and the decrease in nutrients and suspended solids from the inner to the outer bay suggest that the sewage effluent from the inner bay is rapidly diluted and appears to have a limited effect on the phytoplankton of the adjacent waters beyond Deep Bay. Therefore, physical processes play a key role in reducing the risk of algal blooms and hypoxic events in Deep Bay. © 2009 Coastal and Estuarine Research Federation.published_or_final_versionSpringer Open Choice, 01 Dec 201

Preparation of hierarchical porous carbon derived from averrhoa bilimbi and its diffusion properties

In this study, a hierarchically porous carbon was prepared from a natural material, Averrhoa bilimbi, also known as bilimbi. The bilimbis were cut into preferred shape and size before drying by freeze drying method. The bilimbis were then subjected to pyrolysis at temperature of 400°C and transformed to porous carbon. Scanning electron microscopy (SEM) revealed that the bilimbis have a hierarchically porous structure in the macro-range. The diameter of the porosity decreased inwards from 30 to 8μm. Different types of motor oil, which were used to represent bulky molecules, were employed to test the diffusivity of these molecules from the bilimbi. It was found that the oils were able to diffuse through the hierarchically porous bilimbi in 2 to 3 hours, depending on the viscosity of the oils. Therefore, it can be concluded that, Averrhoa bilimbi possesses hierarchical porous structure with interconnected pores and capability to diffuse bulky molecules

Biodiesel Produced from Catalyzed Transesterification of Triglycerides Using ion-Exchanged Zeolite Beta and MCM-22

AbstractIn this work, biodiesel production from catalyzed transesterification of triglycerides with excess methanol was studied by using ion-exchanged Zeolite Beta and MCM-22 as heterogeneous catalysts. Zeolite Beta and MCM-22 were synthesized with hydrothermal processes and, subsequently, modified by ion-exchanged with alkali ions. These as-obtained zeolite catalysts could yield a high conversion of triglycerides to biodiesel. The conversion efficiency was largely affected by crystallinity and frameworks of zeolite support, pH value of alkali ion-exchange solutions and alkali loadings onto the zeolite support. Furthermore, the effects of the duration of the sodium ion-exchange process on the final conversion efficiency of triolein to biodiesel, both the as-prepared Zeolite MCM-22 and Zeolite Beta catalysts were used. The effect of the duration of the sodium ion-exchange process is insignificant in transesterification using Na-ion-exchanged Zeolite MCM-22 catalysts from 0.5 to 4h. In contrast, the conversion efficiency of triolein to biodiesel reached ca. 95% in 0.5hours of transesterification using Zeolite Beta ion-exchanged with 3 mmol-eq. Na+/g cat for 0.5hours