2,623 research outputs found

    Interbasin Water Transfers and Water Scarcity in a Changing World: A Solution or a Pipedream?

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    The world is increasingly forced to face the challenge of how to ensure access to adequate water resources for expanding populations and economies, whilst maintaining healthy freshwater ecosystems and the vital services they provide. Now the growing impacts of climate change are exacerbating the problem of water scarcity in key regions of the world. One popular way for governments to distribute water more evenly across the landscape is to transfer it from areas with perceived surpluses, to those with shortages.While there is a long history of water transfers from ancient times, as many societies reach the limits of locally renewable water supplies increasingly large quantities of water are being moved over long distances, from one river basin to another. Since the beginning of dam building that marked the last half of the 1900s more that 364 large-scale interbasin water transfer schemes (IBTs) have been established that transfer around 400 km³ of water per year (Shiklomanov 1999). IBTs are now widely touted as the quick fix solution to meeting escalating water demands. One estimate suggests that the total number of largescale water transfer schemes may rise to between 760 and 1 240 by 2020 to transfer up to 800 km³ of water per year (Shiklomanov 1999).The wide range of IBT projects in place, or proposed, has provoked the preparation of this review, including seven case studies from around the globe. It builds on previous assessments and examines the costs and benefits of large scale IBTs. This report assesses related, emerging issues in sustaining water resources and ecosystems, namely the virtual water trade, expanding use of desalination, and climate change adaptation. It is based on WWF's 2007 publication "Pipedreams? Interbasin water transfers and water shortages".The report concludes that while IBTs can potentially solve water supply issues in regions of water shortage - they come with significant costs. Large scale IBTs are typically very high cost, and thus economically risky, and they usually also come with significant social and environmental costs; usually for both the river basin providing and the river basin receiving the water

    Analysis of the dynamic response of a long span bridge using GPS/accelerometer/anemometer under typhoon loading

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    Large flexible engineering structures, such as long span bridges or tall buildings, are susceptible to quasistatic and dynamic deformations caused by different loadings, thus accurate displacement measurements are desirable to assess the integrity and reliability of the structure. In this study, an integrated system that includes Global Positioning System (GPS), accelerometer and anemometer was developed to obtain the responses of a long span bridge to the extreme wind loadings. Spectral analysis based on the Fast Fourier Transform (FFT) algorithm was first carried out to detect the dominant frequencies of the middle pylon. Then the noisy GPS displacement measurements and accelerometer data are de-noised using the Vondrak filter, and the low frequency disturbance was separated from GPS displacement time series. A least-squares based displacement reconstruction scheme using noise-mitigated accelerations was employed, and the Tikhonov regularization scheme with optimal selected regularization factor was used to alleviate the ill-posedness. At last, an adaptive recursive least squares (RLS) filter was adopted to separate the slow-varying movements, and the total displacement with enhanced measurement accuracy was obtained from the combined quasi-static and high-frequency dynamic displacements. A field monitoring data set collected on the Erqi Yangtze River Bridge, a three-tower cable-stayed bridge located in Wuhan, China, was used to validate the effectiveness of the proposed integration processing scheme. The GPS/accelerometer/anemometer installed on the center supporting tower was used to characterize the interaction between the responses and the ambient wind loadings. The results demonstrate the proposed technique can significantly improve the measurement accuracy of pylon displacement under strong winds. The deformation accuracy with the amplitude of several millimeters can be successfully detected,and the spectrum of the pylon response obtained from both GPS data and accelerometer data reveals the identified first dominant frequency of the middle pylon is 0.172 Hz

    贴片式动态心电记录仪在临床教学中可行性研究

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    Objective: To explore effectiveness of clinical application of the patch type dynamic ecg recorder by comparing with conventional dynamic ecg recorder Holter. And the clinical ecg teaching models is discussed in this paper. Methods: Using parallel controlled trial method, 60 patients in two hospitals received Holter examination, and patch heart testing at the same time. A comparative analysis of two kinds of inspection methods on testing the average heart rate, supraventricular premature beats and ventricular premature beat was made. Results: The average heart rate of patch type ECG and Holter were 71.87±9.28 and 72.55±9.06 (P = 0.0879). Two kinds of detection methods, chamber on the coincidence rate of premature beat (PPS) was 98.33%, 95% CI (91.06, 99.96), Kappa = 0.9462, 95% CI (0.84, 1.00), good consistency. The accuracy of ventricular premature beat (PPS) was 98.33%, 95% CI (91.06, 99.63), Kappa = 0.9850, 95% CI (0.90, 1.00), good consistency. Patch type heart all platform is suitable for self-study and clinical care study, and professional skill assessment,etc.Conclusion: The effectiveness of patch type heart all on testing the average heart rate, supraventricular premature beat is the same as Holter. it is also suitable for to carry out clinical ECG teaching at the same time.目的 通过和常规动态心电记录仪 Holter比较,研究贴片式的动态心电记录仪临床应用的有效性。并探讨其在临床心电教学中的模式。方法 采用自身平行对照试验方法,在两医院60例患者用Holter检查时,同时用贴片心电仪检测,比较分析两种检查方法在检测平均心率、室上性早搏和室性早搏方面的情况。结果 贴片式心电仪和Holter的平均心率分别为71.87±9.28和72.55±9.06(P=0.0879)。两种检测方法,室上性早搏的符合率(PPS)为 98.33%,95%CI为(91.06,99.96),Kappa=0.9462, 95%CI为(0.84,1.00),一致性良好。室性早搏的符合率(PPS)为 98.33%,95%CI为(91.06,99.63),Kappa=0.9850, 95%CI为(0.90, 1.00)。贴片式心电仪平台适合自学、临床监护学习、大课和专业技能考核等临床心电教学。结论 贴片式心电仪在检测平均心率、室上性早搏和室性早搏方面的有效性和Holter相同。同时也适合以此平台开展临床心电教学

    Mycoplasma hyorhinis infection in gastric carcinoma and its effects on the malignant phenotypes of gastric cancer cells

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    <p>Abstract</p> <p>Background</p> <p><it>Mycoplasma hyorhinis </it>infection has been postulated to play a role in the development of several types of cancer, but the direct evidence and mechanism remained to be determined.</p> <p>Methods</p> <p>Immunohistochemistry assay and nested polymerase-chain reaction (PCR) were performed to examine the <it>mycoplasma hyorhinis </it>infection in gastric cancer tissues. Statistical analysis was used to check the association between mycoplasma infection and clinicopathologic parameters. Transwell chamber assay and metastasis assay were used to evaluate <it>mycoplasma hyorhinis</it>' effects on metastasis in vitro and in vivo. <it>Mycoplasma hyorhinis</it>-induced extracellular signal-regulated kinase (ERK) and epidermal growth factor receptor (EGFR) activation were investigated by Western blot.</p> <p>Results</p> <p>My<it>coplasma hyorhinis </it>infection in gastric cancer tissues was revealed and statistical analysis indicated a significant association between mycoplasma infections and lymph node metastasis, Lauren's Classification, TNM stage, and age of the patients. <it>Mycoplasma hyorhinis </it>promoted tumor cell migration, invasion and metastasis <it>in vitro </it>and <it>in vivo</it>, which was possibly associated with the enhanced phosphorylation of EGFR and ERK1/2. The antibody against p37 protein of <it>Mycoplasma hyorhinis </it>could inhibit the migration of the infected cells.</p> <p>Conclusions</p> <p>The infection of <it>m</it>y<it>coplasma hyorhinis </it>may contribute to the development of gastric cancer and <it>Mycoplasma hyorhinis</it>-induced malignant phenotypes were possibly mediated by p37.</p

    4,4′-Bipyridinium bis(perchlorate)–4-aminobenzoic acid–4,4′-bipyridine–water (1/4/2/2)

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    In the structure of the title compound, C10H10N2 2+·2ClO4 −·4C7H7NO2·2C10H8N2·2H2O, the 4,4′-bipyridinium cation has a crystallographically imposed centre of symmetry. The cation is linked by N—H⋯N hydrogen bonds to adjacent 4,4′-bipyridine mol­ecules, which in turn inter­act via O—H⋯N hydrogen bonds with 4-amino­benzoic acid mol­ecules, forming chains running parallel to [30]. The chains are further connected into a three-dimensional network by N—H⋯O and O—H⋯O hydrogen-bonding inter­actions involving the perchlorate anion, the water mol­ecules and the 4-amino­benzoic acid mol­ecules. In addition, π–π stacking inter­actions with centroid–centroid distances ranging from 3.663 (6) to 3.695 (6) Å are present. The O atoms of the perchlorate anion are disordered over two sets of positions, with refined site occupancies of 0.724 (9) and 0.276 (9)
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