422 research outputs found

    Why Chinese airlines haven’t become leading cargo carriers - analyzing air freight network and international trade drivers for mainland China

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    In contrast to the tremendous growth in the passenger sector, Chinese airlines and logistics operators still play relatively minor roles in the world’s air cargo market. This study investigates the air freight network within mainland China using complex network analysis, and identifies the key drivers for international trade delivered by air with an augmented gravity model. Our network analysis suggests that domestic air freights flow through a relatively small point-to-point network. Demands are concentrated in the catchments of metropolitan regions, where passenger hubs have not served as cargo gateways. International air cargo flow is more balanced than China’s overall merchandise trade. As a result, foreign carriers can cherry-pick the most lucrative markets and link them to their global networks. Gravity model estimation suggests that for China’s international trade by air, the composition of the economy is a more important driver than the simple size of the economy. Therefore, air freight demand in China was not as high as past GDP numbers suggested, but is likely to outpace overall economic growth in the years to come. This should help Chinese airlines to achieve their cargo ambitions in the long term

    Flexible Surface Acoustic Wave Humidity Sensor with on Chip Temperature Compensation

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    AbstractThis paper reports the development of flexible surface acoustic wave (SAW) based humidity sensors on polyimide substrate. The SAW devices have two resonant peaks, named the A0 and S0 Lamb modes, which have different temperature coefficients of frequency. Graphene oxide (GO) is used as the sensing layer owing to its large surface area and hydrophilcity to water. The sensors show high sensitivity up to 145.83ppm/%RH, comparable to those on rigid substrates, and fast response time of 4.4s. The sensitivity increases with the increase of GO thickness and resonant frequency. By utilizing the S0 mode as the temperature reference, a SAW Humidity-sensor with an on chip temperature compensation capability is demonstrated. The humidity sensors also show the ability to work under severe bending condition, demonstrated its great potential for flexible/wearable applications

    Electrolysis of Converter Matte in Molten CaCl2-NaCl

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    The electrolytic production of nickel-copper alloy by electrochemical reduction of converter matte in molten salt has been investigated. The sintered solid porous pellets of Ni3S2, Cu2S and converter matte were electrolyzed at a voltage of 3.0 V in molten CaCl2-NaCl under the protection of argon gas at 700?, respectively. The electro-reduction processes were investigated and the products were characterized. The results show that the molten salt electro-reduction process can be used to produce nickel, copper and nickel-copper alloy directly from Ni3S2, Cu2S and converter matte precursors in molten CaCl2-NaCl, respectively. CaS would be formed as the intermediate compound during the electro-reduction process, and then the formed CaS can be gradually decomposed and removed with the increase of the electrolysis time. The experimental results show that the molten salt electro-reduction process has the potential to be used for the reduction of sulfide minerals in molten CaCl2-NaClpublishersversionPeer reviewe

    Recombination analysis based on the complete genome of bocavirus

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    Bocavirus include bovine parvovirus, minute virus of canine, porcine bocavirus, gorilla bocavirus, and Human bocaviruses 1-4 (HBoVs). Although recent reports showed that recombination happened in bocavirus, no systematical study investigated the recombination of bocavirus. The present study performed the phylogenetic and recombination analysis of bocavirus over the complete genomes available in GenBank. Results confirmed that recombination existed among bocavirus, including the likely inter-genotype recombination between HBoV1 and HBoV4, and intra-genotype recombination among HBoV2 variants. Moreover, it is the first report revealing the recombination that occurred between minute viruses of canine

    High sensitivity flexible Lamb-wave humidity sensors with a graphene oxide sensing layer

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    This paper reports high performance flexible Lamb wave humidity sensors with a graphene oxide sensing layer. The devices were fabricated on piezoelectric ZnO thin films deposited on flexible polyimide substrates. Two resonant peaks, namely the zero order antisymmetric (A0) and symmetric (S0) mode Lamb waves, were observed and fitted well with the theoretical analysis and modelling. With graphene oxide microflakes as the sensing layer, the sensing performance of both wave modes was investigated. The humidity sensitivity of the A0 mode is 145.83 ppm per %RH (at humidity 85%RH), higher than that of S0 mode of 89.35 ppm per %RH. For the first time, we have demonstrated that the flexible humidity sensors work as usual without noticeable deterioration in performance even under severe bending conditions up to 1500 με. Also the sensors showed an excellent stability upon repeated bending for thousand times. All the results demonstrated that the Lamb wave flexible humidity sensors have a great potential for application in flexible electronics

    Abnormal expression of an ADAR2 alternative splicing variant in gliomas downregulates adenosine-to-inosine RNA editing

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    BACKGROUND: RNA editing is catalyzed by adenosine deaminases acting on RNA (ADARs). ADAR2 is the main enzyme responsible for recoding editing in humans. Adenosine-to-inosine (A-to-I) editing at the Q/R site is reported to be decreased in gliomas; however, the expression of ADAR2 mRNA was not greatly affected. METHODS: We determined ADAR2 mRNA expression in human glioblastoma cell lines and in normal human glial cells by real-time RT-PCR. We also determined ADAR2 mRNA expression in 44 glioma tissues and normal white matter. After identifying an alternative splicing variant (ASV) of ADAR2 in gliomas, we performed sequencing. We then classified glioblastomas based on the presence (+) or absence (–) of the ASV to determine the correlations between ASV + and malignant features of glioblastomas, such as invasion, peritumoral brain edema, and survival time. RESULTS: There were no significant differences in ADAR2 mRNA expression among human glioblastoma cell lines or in gliomas compared with normal white matter (all p > 0.05). The ASV, which contained a 47-nucleotide insertion in the ADAR2 mRNA transcript, was detected in the U251 and BT325 cell lines, and in some glioma tissues. The expression rate of ASV differed among gliomas of different grades. ASV + glioblastomas were more malignant than ASV – glioblastomas. CONCLUSIONS: ADAR2 is a family of enzymes in which ASVs result in differences in enzymatic activity. The ADAR2 ASV may be correlated with the invasiveness of gliomas. Identification of the mechanistic characterization of ADAR2 ASV may have future potential for individualized molecular targeted-therapy for glioma

    Modeling Hidden Nodes Collisions in Wireless Sensor Networks: Analysis Approach

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    This paper studied both types of collisions. In this paper, we show that advocated solutions for coping with hidden node collisions are unsuitable for sensor networks. We model both types of collisions and derive closed-form formula giving the probability of hidden and visible node collisions. To reduce these collisions, we propose two solutions. The first one based on tuning the carrier sense threshold saves a substantial amount of collisions by reducing the number of hidden nodes. The second one based on adjusting the contention window size is complementary to the first one. It reduces the probability of overlapping transmissions, which reduces both collisions due to hidden and visible nodes. We validate and evaluate the performance of these solutions through simulations
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