12,438 research outputs found

    A small segmented oscillating water column using a savonius rotor turbine

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    This paper outlines a project which addresses the use of a small segmented oscillating water column with three sections. The turbine utilises cascaded Savonius rotors (one for each section) and this system is developed and tested for validation of the performance algorithms. It is shown that the systems can be easily described and a system developed that can generate. It would be suitable for a shoreline location such as a harbour wall, where waves are random and not orthogonal to the column. Conversion rates in the region of 20 % are tabulated for the system with an output of 25 W peak. The paper will give a full algorithm for the system while the digest outlines some crucial points with regards to the sizing and operation of the column with respect to the wave frequency and wavelength. The turbine is fully characterized - the generator is a brushless permanent magnet machine connected to a diode bridge rectifier and variable load. © 2008 IEEE

    Reconstructing the Star Formation History of the Galaxy

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    The evolution of the star formation rate in the Galaxy is one of the key ingredients quantifying the formation and determining the chemical and luminosity evolution of galaxies. Many complementary methods exist to infer the star formation history of the components of the Galaxy, from indirect methods for analysis of low-precision data, to new exact analytic methods for analysis of sufficiently high quality data. We summarise available general constraints on star formation histories, showing that derived star formation rates are in general comparable to those seen today. We then show how colour-magnitude diagrams of volume- and absolute magnitude-limited samples of the solar neighbourhood observed by Hipparcos may be analysed, using variational calculus techniques, to reconstruct the local star formation history. The remarkable accuracy of the data coupled to our maximum-likelihood variational method allows objective quantification of the local star formation history with a time resolution of ~ 50 Myr. Over the past 3Gyr, the solar neighbourhood star formation rate has varied by a factor of ~ 4, with characteristic timescale about 0.5Gyr, possibly triggered by interactions with spiral arms.Comment: 12 pages, Proc. of the Sept. 20-24, 1999 Vulcano Workshop ``The chemical evolution of the Milky Way: stars vs. clusters'', eds. F. Matteucci & F. Giovanell

    A secret image sharing scheme for light images

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    Cancer gene therapy targeting angiogenesis: An updated review

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    Since the relationship between angiogenesis and tumor growth was established by Folkman in 1971, scientists have made efforts exploring the possibilities in treating cancer by targeting angiogenesis. Inhibition of angiogenesis growth factors and administration of angiogenesis inhibitors are the basics of anti-angiogenesis therapy. Transfer of anti-angiogenesis genes has received attention recently not only because of the advancement of recombinant vectors, but also because of the localized and sustained expression of therapeutic gene product inside the tumor after gene transfer. This review provides the up-to-date information about the strategies and the vectors studied in the field of anti-angiogenesis cancer gene therapy. © 2006 The WJG Press. All rights reserved.published_or_final_versio

    Microbiological evaluation of the Mhlathuze River, KwaZulu-Natal (RSA)

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    Continuous faecal pollution in source water is a global problem that is particularly debilitating to rural communities that are directly dependent on untreated source water for all their domestic and other purposes. The elevation of indicator bacteria levels (such as the faecal coliforms) in the water may pose a public health risk. This study reports the results of microbial monitoring of the Mhlathuze River over a 21-month period. Elevated levels of indicator micro-organisms (both faecal and total coliforms) and heterotrophic plate count bacteria were observed from March 1998 to November 1999. Surface water temperature and rainfall during this period appeared to be some of the factors affecting the increased bacterial counts. Bacteria isolated from the river included E. coli, Pseudomonas spp., Enterobacter spp. (detected frequently), Serratia spp., Klebsiella spp., and Aeromonas hydrophila (detected less frequently). This study generated some essential baseline information of the microbial population for a section of the river utilised for domestic, agricultural and industrial purposes. WaterSA Vol.28(3) 2002: 281-28

    Risk Factors for Unplanned Early Implantable Port Catheter Removal in Adult Hematology Cancer Patients Receiving Chemotherapy: A Propensity Score Matching Study

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    Ming-Shian Lu,1,2 Chih-Chen Chen,2,3 Che-Chia Chang,1 Chien-Chao Lin,1 Ching-Chuan Hsieh1,2 1Department of Surgery, Chang Gung Memorial Hospital at Chiayi, Puzi City, Taiwan; 2Department of Medicine, College of Medicine, Chang Gung University, Taoyuan, Taiwan; 3Department of Medicine, Chang Gung Memorial Hospital at Chiayi, Puzi City, TaiwanCorrespondence: Ching-Chuan Hsieh, Department of Surgery, Chang Gung Memorial Hospital at Chiayi, 8, West Sec, Jiapu Road, Puzi City, Chiayi, 613016, Taiwan, Tel +886 5 362100 Ext 2860, Fax +886- 5 3623002, Email [email protected]: Implantable port catheter is a reliable vascular access for chemotherapy infusion in cancer patients. However, patients with hematology malignancies usually present with a myriad of blood cell abnormalities that put them at risk of infection and mechanical problems requiring catheter removal. This study aims to determine the risk factors associated with unplanned (catheter removal other than completion of treatment plan) early (within 90 days of catheter implantation) implantable port catheter removal.Patients and Methods: A retrospective, propensity score-matched study of 386 patients with hematology malignancies who received implantable venous access ports between January 2015 and December 2022. We conducted a univariate analysis to select the variables for propensity score matching. Patients with unplanned early implantable port catheter removal (early group) were matched 1:1 to patients without unplanned early removal (non-early group).Results: Univariate analysis demonstrated a statistically significant difference between early and non-early groups for age (p = 0.048), hemoglobin level (p = 0.028), thrombocytopenia (p = 0.025), and PG-SGA (p < 0.001). Thrombocytopenia was the only independent risk factor with a statistically significant difference in Cox proportional hazard analysis, HR 2.823, 95 CI 1.050– 7.589, p = 0.040. The median catheter survival for patients with thrombocytopenia was 61 days (95% CI 28.58– 93.42) compared to 150 days (95% CI 9.81– 290.19) for patients without thrombocytopenia, p = 0.015. Patient survival is not affected by early catheter removal. The median survival for patients in the early group was 28.28 months (95% CI 27.43– 29.15) compared to 32.39 months (95% CI 24.11– 40.68), for the non-early group, p = 0.709.Conclusion: Hematology malignancy patients with thrombocytopenia are at high risk for unplanned early port catheter removal without survival difference.Keywords: hematology, malignancy, vascular port, risk factors, explanatio

    Impact of soft handover and pilot pollution on video telephony in a commercial network

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    Soft handover (SHO) provides better support for user mobility. The quality of service (QoS) to the mobile wireless subscribers can also grant benefits from SHO. To analyze the impact of SHO on the circuit switched (CS) video telephony (VT); real-time measurements have been conducted on a commercial WCDMA mobile network in the CBD of Sydney, Australia. Live measurement provides a practical approach to evaluate performance of commercial network. The obtained SHO gain implies that better QoS can be achieved. Furthermore, the negative impact of pilot pollution on radio link quality has been demonstrated in this paper. ©2010 IEEE
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