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Now showing items 97 - 112 of 297

  • Evaluating the effects of area closure for recreational fishing in a coral reef ecosystem: The benefits of an integrated economic and biophysical modeling

    Lei Gao   Atakelty Hailu  

    This paper presents an integrated agent-based model of recreational fishing behavior within a reef ecosystem as a platform for the evaluation of recreational fishing management strategies. Angler behavior is described using econometrically estimated site choice models, with site choice among anglers driven by site attributes and angler characteristics. The biophysical model represents the marine reef environment as a system with different trophic levels identifying algal and coral growth as well as two types of fish (piscivores and herbivores). Ecosystem dynamics are driven by interactions within the trophic levels and interaction between fish populations and fishing activities. The model is used to simulate recreational fishing activities and their interactions with the environment. Recreational fishing sites from the Ningaloo Marine Park, an iconic coral reef system in Western Australia, are used as a case study. A set of management strategies, including "business-as-usual" and different site closure durations, are assessed for two different levels of fishing pressures. The results show that not only the effectiveness but also the distribution of management impacts across space and over time can be very different from what one would expect without the benefit of integrated modeling. (C) 2011 Elsevier B.V. All rights reserved.
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  • Suppressive Effects of Quercetin-3-O-(6″-Feruloyl)-β-D-Galactopyranoside on Adipogenesis in 3T3-L1 Preadipocytes Through Down-regulation of PPAR and C/EBP Expression

    Lei Yang   Xiao-Fan Li   Lei Gao   Ya-Ou Zhang and Guo-Ping Cai  

    Obesity is a chronic, costly disease, and flavonoids such as quercetin have been proven to play protective roles against it. This study investigated the suppressive effect of quercetin-3-O-(6″-feruloyl)-β-D-galactopyranoside (QFG) on adipogenesis of 3T3-L1 preadipocytes. Quercetin-3-O-(6″-feruloyl)-β-D-galactopyranoside and quercetin were both extracted from Psidium guajava (Myrtaceae, commonly known as guava) leaves and were evaluated for their suppressive effect on adipogenesis by means of oil red O staining and triglyceride assay. It was shown that QFG inhibited adipogenesis in a dose- and time-dependent manner, and it exerted a stronger effect than did quercetin at the same concentration. Quantitative real-time polymerase chain reaction and western blotting were conducted to further examine the differentiation expression of marker genes and transcriptional factors. Both mRNA and protein expression of the key adipogenic transcriptional factors, peroxisome proliferator-activated receptor gamma (PPAR) and CCAAT (cytidine-cytidine-adenosine-adenosine-thymidine)/enhancer-binding protein alpha (C/EBP), were inhibited by QFG. Moreover, the mRNA expression patterns of key participants in the Wnt–β-catenin pathway were not altered during the QFG-induced adipogenesis inhibition. These results suggest that QFG effectively suppresses adipogenesis and that it exerts its role mainly through the significant down-regulation of PPAR and C/EBP and, probably, via a Wnt–β-catenin independent pathway. Copyright
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  • Ranking management strategies with complex outcomes: An AHP-fuzzy evaluation of recreational fishing using an integrated agent-based model of a coral reef ecosystem

    Lei Gao   Atakelty Hailu  

    The management of recreational fishing requires resolving conflicting interests and is thus among the most controversial natural resource related issues. Decision making is difficult because of two main factors: first, there is lack of prediction tools that help managers and other stakeholders assess the potential impacts of management changes; second, decisions or management strategies affect multiple social and ecological outcomes and picking the best among sets of multiple outcomes is a complex task. Resource management and stakeholder dialogue can be greatly improved by addressing these problems. In this paper, we propose a decision support system (DSS) for assessing management strategies. The DSS incorporates an integrated agent-based simulation model for tackling the first obstacle and an analytical hierarchy process (AHP)-fuzzy comprehensive evaluation approach to facilitate multi-criteria decision making.The agent-based simulation model incorporates recreational fishing behaviour within a reef ecosystem. Angler behaviour is driven by empirically estimated site choice models which link recreational choices to site attributes and angler characteristics. Coral reef ecosystem dynamics is modelled using a trophic-dynamic model describing the relationship among fish populations, fishing activities as well as algal and coral growth. The second component of the DSS, the AHP-fuzzy comprehensive evaluation part, allows one to combine resource managers?preferences with simulated economic and ecosystem outcomes in the assessment of alternative strategies. A fuzzy multi-criteria, multi-layer evaluation method is used to obtain final ranking.As a case study for this paper, we focus on the management of recreational fishing sites from the Ningaloo Marine Park, an iconic coral reef system in Western Australia. A set of management strategies, including a “business-as-usual?strategy and alternative site closure strategies are assessed using the proposed DSS. The site closure strategies evaluated vary in length and timing. Further, these evaluations are undertaken for two fishing pressure scenarios (high and low). We illustrate the usefulness of the DSS by evaluating these strategies. We also present some results from a sensitivity analysis focussing on changes in preferences.
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  • ChemInform Abstract: Synthesis of a Novel Series of (E,E)-4,6-Bis(styryl)-2-O-glycopyranosyl-pyrimidines and Their Potent Multidrug Resistance (MDR) Reversal Activity Against Cancer Cells.

    Lei Gao   Qian Liu   Sumei Ren   Shengbiao Wan   Tao Jiang   Iris L. K. Wong   Larry M. C. Chow and Shixi Wang  

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  • Inverse association between a pro-inflammatory genetic profile and Helicobacter pylori seropositivity among patients with chronic atrophic gastritis: Enhanced elimination of the infection during disease progression?

    Lei Gao   Melanie N. Weck   Alexandra Nieters   Hermann Brenner  

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  • 13C?NMR as a primary method for determining saturates, cis- and trans-monounsaturates and polyunsaturates in fats and oils for nutritional labeling purposes

    Lei Gao   Jaqueline Sedman   Diego L. García-González   Sadia Ehsan   Tara Sprules   Frederik R. van de Voort  

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  • [IEEE 2011 3rd International Conference on Computer Research and Development (ICCRD) - Shanghai, China (2011.03.11-2011.03.13)] 2011 3rd International Conference on Computer Research and Development - Research on implementation of software test management

    Lei Gao  

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  • BDgene: a genetic database for bipolar disorder and its overlap with schizophrenia and major depressive disorder.

    Su-hua Chang   Lei Gao   Zhao Li   Wei-na Zhang   Yang Du   Jing Wang  

    BACKGROUND Bipolar disorder (BD) is a common psychiatric disorder with complex genetic architecture. It shares overlapping genetic influences with schizophrenia (SZ) and major depressive disorder (MDD). Large numbers of genetic studies of BD and cross-disorder studies between BD and SZ/MDD have accumulated numerous genetic data. There is a growing need to integrate the data to provide a comprehensive data set to facilitate the genetic study of BD and its highly relevant diseases. METHODS BDgene database was developed to integrate BD-related genetic factors and shared ones with SZ/MDD from profound literature reading. On the basis of data from the literature, in-depth analyses were performed for further understanding of the data, including gene prioritization, pathway-based analysis, intersection analysis of multidisease candidate genes, and pathway enrichment analysis. RESULTS BDgene includes multiple types of literature-reported genetic factors of BD with both positive and negative results, including 797 genes, 3119 single nucleotide polymorphisms, and 789 regions. Shared genetic factors such as single nucleotide polymorphisms, genes, and regions from published cross-disorder studies among BD and SZ/MDD were also presented. In-depth data analyses identified 43 BD core genes; 70 BD candidate pathways; and 127, 79, and 107 new potential cross-disorder genes for BD-SZ, BD-MDD, and BD-SZ-MDD, respectively. CONCLUSIONS As a central genetic database for BD and the first cross-disorder database for BD and SZ/MDD, BDgene provides not only a comprehensive review of current genetic research but also high-confidence candidate genes and pathways for understanding of BD mechanism and shared etiology among its relevant diseases. BDgene is freely available at http://bdgene.psych.ac.cn.
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  • Band engineering of honeycomb monolayer CuSe via atomic modification

    Lei Gao   Yan-Fang Zhang   Jia-Tao Sun   Shixuan Du  

    Two-dimensional monolayer copper selenide(CuSe)has been epitaxially grown and predicted to host the Dirac nodal line fermion(DNLF).However,the metallic state of monolayer CuSe inhibits the potential application of nanoelectronic devices in which a band gap is needed to realize on/off properties.Here,we engineer the band structure of monolayer CuSe which is an analogue of a p-doped system via external atomic modification in an effort to realize the semiconducting state.We find that the H and Li modified monolayer CuSe shifts the energy band and opens an energy gap around the Fermi level.Interestingly,both the atomic and electronic structures of monolayer CuHSe and CuLiSe are very different.The H atoms bind on top of Se atoms of monolayer CuSe with Se-H polar covalent bonds,annihilating the DNLF band of monolayer CuSe dominated by Se orbitals.In contrast,Li atoms prefer to adsorb at the hexagonal center of CuSe,preserving the DNLF band of monolayer CuSe dominated by Se orbitals,but opening band gaps due to a slight buckling of the CuSe layer.The realization of metal-to-semiconductor transition from monolayer CuSe to CuXSe(X=H,Li)as revealed by first-principles calculations makes it possible to use CuSe in future electronic devices.
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  • A systems model combining process-based simulation and multi-objective optimisation for strategic management of mine water

    Lei Gao   Damian Barrett   Yun Chen   Mingwei Zhou   Susan Cuddy   Zahra Paydar   Luigi Renzullo  

    Abstract This paper presents a hierarchical systems model, which integrates a simulator of the mine water use process with a multi-objective optimiser for assessing mine water management strategies. The simulator advances prior tools in simulating complicated strategies by placing operation rules on model objects and process states. An optimisation framework that interacts with the simulator is used to identify optimal strategies for water storage, use and reuse that are ‘fit-for-purpose’, easy to handle, and economic. The model has been used to assess mine water use strategies in a coal mine in Queensland, Australia. The simulation results indicate that some tested strategies could reduce water use costs by more than 40%, and raw water needed by more than 50%. Further, the optimisation revealed more easy-to-handle strategies that could save more than 40% of pipeline water and reduce the risks of penalties associated with discharge and of losing production due to insufficient water. Highlights • We present an object-oriented system model for assessing mine water management strategies. • The model combines the capabilities of water use process-based simulation and multi-objective optimisation. • The system model can simulate complicated strategies by placing operation rules on model objects and process states. • The system model can be used for investigating optimal strategy solutions that meet potentially conflicting objectives. • A case study illustrates the value of the system model.
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  • A highly selective fluorescent chemosensor for CN<sup>−</sup> based on a novel bis(salamo)-type tetraoxime ligand

    Fei Wang   Lei Gao   Qing Zhao   Yang Zhang   Wen-Kui Dong   Yu-Jie Ding  

    Abstract The optical properties of a novel chemosensor for cyanide anions based on a symmetric bis(salamo)-type ligand (H 3 L) were investigated by UV–Vis and fluorescence spectroscopy in MeOH/H 2 O (1:1 v/v) solution. Sensor H 3 L can selectively sense CN − based on prominent color changes among other anions. The chemosensor exhibits an apparent fluorescence enhancement at 482 nm to CN − which because cyanide ions interact with C N bonds. Combining the corrected Benesi-Hildebrand formula, the binding constant of the formed host-guest complex was calculated as 2.42 × 10 5 M − 1 . Meanwhile, the detection limit of the sensor toward CN − was 8.91 × 10 − 7 M. It is worth noting that the designed sensor can be used for rapid detection of cyanide anions in basic pH range, and has great practical value. Graphical Abstract Through the interaction of CN − with a novel bis(salamo)-type tetraoxime ligand H 3 L, a new chemosensor for cyanide anion was obtained. Sensor H 3 L can selectively sense CN − based on prominent color changes among other anions. Image 2 Highlights • A new chemosensor (H 3 L) for CN − was synthesized. Sensor H 3 L can selectively sense CN − based on color changes. • The chemosensor exhibited an obvious fluorescence enhancement at 482 nm to CN − which because CN − interact with C N. • It is worth noting that the sensor can be used for rapid detection of cyanide anions in basic pH range.
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  • Whole genome molecular phylogeny of large dsDNA viruses using composition vector method

    Lei Gao   Ji Qi  

    BackgroundOne important mechanism by which large DNA viruses increase their genome size is the addition of modules acquired from other viruses, host genomes or gene duplications. Phylogenetic analysis of large DNA viruses, especially using methods based on alignment, is often difficult due to the presence of horizontal gene transfer events. The recent composition vector approach, not sensitive to such events, is applied here to reconstruct the phylogeny of 124 large DNA viruses.ResultsThe results are mostly consistent with the biologist's systematics with only a few outliers and can also provide some information for those unclassified viruses and cladistic relationships of several families.ConclusionWith composition vector approach we obtained the phylogenetic tree of large DNA viruses, which not only give results comparable to biologist's systematics but also provide a new way for recovering the phylogeny of viruses.
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  • Prolonged CT urography in duplex kidney

    Hong-han Gong   Lei Gao   Xi-jian Dai   Fuqing Zhou   Ning Zhang   Xianjun Zeng   Jian Jiang   Laichang He  

    BACKGROUND Duplex kidney is a common anomaly that is frequently associated with multiple complications. Typical computed tomography urography (CTU) includes four phases (unenhanced, arterial, parenchymal and excretory) and has been suggested to considerably aid in the duplex kidney diagnosi. Unfortunately, regarding duplex kidney with prolonged dilatation, the affected parenchyma and tortuous ureters demonstrate a lack of or delayed excretory opacification. We used prolonged-delay CTU, which consists of another prolonged-delay phase (1- to 72-h delay; mean delay: 24 h) to opacify the duplicated ureters and affected parenchyma. METHODS Seventeen patients (9 males and 8 females; age range: 2.5-56 y; mean age: 40.4 y) with duplex kidney were included in this study. Unenhanced scans did not find typical characteristics of duplex kidney, except for irregular perirenal morphology. Duplex kidney could not be confirmed on typical four-phase CTU, whereas it could be easily diagnosed in axial and CT-3D reconstruction using prolonged CTU (prolonged-delay phase). RESULTS Between January 2005 and October 2010, in this review board-approved study (with waived informed consent), 17 patients (9 males and 8 females; age range: 2.5 ~ 56 y; mean age: 40.4 y) with suspicious duplex kidney underwent prolonged CTU to opacify the duplicated ureters and confirm the diagnosis. CONCLUSION Our results suggest the validity of prolonged CTU to aid in the evaluation of the function of the affected parenchyma and in the demonstration of urinary tract malformations.
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  • Effects of assuming constant optical scattering on haemoglobin concentration measurements using NIRS during a Valsalva Manoeuvre

    Lei Gao   Clare E. Elwell   Matthias Kohl-Bareis   Marcus Gramer   Chris E. Cooper   Terence S. Leung   Ilias Tachtsidis  

    Resolving for changes in concentration of tissue chromophores in the human adult brain with near-infrared spectroscopy has generally been based on the assumption that optical scattering and pathlength remain constant. We have used a novel hybrid optical spectrometer that combines multi-distance frequency and broadband systems to investigate the changes in scattering and pathlength during a Valsalva manoeuvre in 8 adult volunteers. Results show a significant increase in the reduced scattering coefficient of 17% at 790nm and 850nm in 4 volunteers during the peak of the Valsalva. However; these scattering changes do not appear to significantly affect the differential pathlength factor and the tissue haemoglobin concentration measurements.
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  • Amplitude of Low-Frequency Fluctuations in Multiple-Frequency Bands in Acute Mild Traumatic Brain Injury

    Jie Zhan   Lei Gao   Fuqing Zhou   Lijun Bai   Hongmei Kuang   Laichang He   Xianjun Zeng   Hong-han Gong  

    Functional disconnectivity during the resting state has been observed in mild traumatic brain injury (mTBI) patients during the acute stage. However, it remains largely unknown whether the abnormalities are related to specific frequency bands of the low-frequency oscillations (LFO). Here, we used the amplitude of low-frequency fluctuations (ALFF) to examine the amplitudes of LFO in different frequency bands (slow-5: 0.01-0.027 Hz; slow-4: 0.027-0.073 Hz; and typical: 0.01-0.08 Hz) in patients with acute mTBI. A total of 24 acute mTBI patients and 24 age-, sex-, and education-matched healthy controls participated in this study. In the typical band, acute mTBI patients showed lower standardized ALFF in the right middle frontal gyrus and higher standardized ALFF in the right lingual/fusiform gyrus and left middle occipital gyrus. Further analyses showed that the difference between groups was concentrated in a narrower (slow-4) frequency band. In the slow-5 band, mTBI patients only exhibited higher standardized ALFF in the occipital areas. No significant correlation between the mini-mental state examination score and the standardized ALFF value was found in any brain region in the three frequency bands. Finally, no significant interaction between frequency bands and groups was found in any brain region. We concluded that the abnormality of spontaneous brain activity in acute mTBI patients existed in the frontal lobe as well as in distributed brain regions associated with integrative, sensory, and emotional roles, and the abnormal spontaneous neuronal activity in different brain regions could be better detected by the slow-4 band. These findings might contribute to a better understanding of local neural psychopathology of acute mTBI. Future studies should take the frequency bands into account when measuring intrinsic brain activity of mTBI patients.
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  • Improving availability and performance with application-specific data replication

    Lei Gao   Dahlin, M.   Nayate, A.   Jiandan Zheng   Arun lyengar  

    The emerging edge services architecture promises to improve the availability and performance of Web services by replicating servers at geographically distributed sites. A key challenge in such systems is data replication and consistency, so that edge server code can manipulate shared data without suffering the availability and performance penalties that would be incurred by accessing a traditional centralized database. This work explores using a distributed object architecture to build an edge service data replication system for an e-commerce application, the TPC-W benchmark, which simulates an online bookstore. We take advantage of application-specific semantics to design distributed objects that each manages a specific subset of shared information using simple and effective consistency models. Our experimental results show that by slightly relaxing consistency within individual distributed objects, our application realizes both high availability and excellent performance. For example, in one experiment, we find that our object-based edge server system provides five times better response time over a traditional centralized cluster architecture and a factor of nine improvement over an edge service system that distributes code but retains a centralized database.
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