645 research outputs found

    Corn and soybean yield responses to micronutrients fertilization

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    Micronutrients such as boron (B), chloride (Cl), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) are essential plant nutrients taken up by crops in very small amounts, but a deficiency can have profound effects on yield because they perform important physiological functions. Deficiencies seldom are observed or are widespread in Iowa and neighboring states. Farmers and crop consultants have been asking questions, however, concerning possible yield loss due to deficiency of micronutrients in corn and soybean

    Radiologic feeding gastrostomy placement: experience in 23 patients

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    Objective: To evaluate the safety, efficacy and complications of percutaneous gastrostomy catheter placementunder flouro guidance for long-term enteral feeding.MATERIALS AND Methods: Between April 1998 to May 2002, 23 patients who had percutaneous gastrostomy catheter placement were retrospectively reviewed. Clinical indications for catheter placement included patients with neurologic disease, head and neck malignancy, and pulmonary disease patients. Placement of 12 - 14 Fr gastrostomy catheter was then accomplished with the Seldinger technique. The technical success, procedural complications were recorded.Results: Twenty seven procedures, including revisions, were performed. The success rate for catheter placement was 100%. Revision was necessary in 7 (30%) instances in 7 patients. There was one (3.8%) major and 4 (14.8%) minor complications.CONCLUSION: Fluoroscopically directed percutaneous placement of gastrostomy catheters is a safe and effective procedure

    Percutaneous transhepatic biliary stenting

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    Objective: Bilary stenting with endoprosthesis is a palliative procedure to relieve malignant biliary obstruction. Percutaneous transhepatic technique has been employed whenever endoscopic technique was not possible or had failed.SETTING: Angiography/intervention suite, department of radiology, Aga Khan University hospital, Karachi.Methods: We present retrospective analysis of 17 patients with malignant jaundice who were treated with percutaneous techniques after the endoscopic route had failed.Results: The success rate was 94% with placement of single plastic stent in 14 patients, double stents in 3 patients and self-expandable stent in one patient. The overall complication rate was 41% including sepsis, liver abscess, biloma formation, biliary leakage and stent occlusion. There was one procedure related death due to severe sepsis.CONCLUSION: Percutaneous transhepatic biliary stenting is an alternative procedure to relieve malignant biliary obstruction with high complication rate and should be reserved for selected patients in whom endoscopic route has failed

    Minimization of total harmonic distortions of cascaded H-bridge multilevel inverter by utilizing bio inspired AI algorithm

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    Minimizing total harmonic distortion (THD) with less system complexity and computation time is a stringent constraint for many power systems. The multilevel inverter can have low THD when switching angles are selected at the fundamental frequency. For low-order harmonic minimization, selective harmonic elimination (SHE) is the most adopted and proficient technique but it involves the non-linear transcendental equations which are very difficult to solve analytically and numerically. This paper proposes a genetic algorithm (GA)-based optimization technique to minimize the THD of cascaded H-bridge multilevel inverter. The GA is the finest approach for solving such complex equations by obtaining optimized switching angles. The switching angles are calculated by the genetic algorithm by solving the nonlinear transcendental equations. This paper has modeled and simulated a five-level inverter in MATLAB Simulink. The THD comparison is carried out between step modulation method and optimization method. The results reveal that THD has been reduced from 17.88 to 16.74% while third and fifth harmonics have been reduced from 3.24%, 3.7% to 0.84% and 3.3%, respectively. The optimization method along with LC filter significantly improves the power quality providing a complete sinusoidal signal for varying load

    Pioneering the human development revolution: Analysing the trajectory of Mahbub ul Haq

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    Mahbub ul Haq's work to coordinate, establish and propagate the human development approach offers an example of effective leadership in promoting more ethical socio-economic development. This article reviews Pioneering the Human Development Revolution-An Intellectual Biography of Mahbub ul Haq (edited by Haq and Ponzio), and extends themes from the United Nations Intellectual History Project to examine Haq's contributions in terms of four aspects of leadership: articulating and applying values that combine depth with broad appeal; providing a fruitful and vivid way of seeing, a 'vision', that reflects the values; embodying the values and vision in workable practical proposals; and supporting and communicating the previous aspects through wide and relevant networks. It suggests that the human development approach may need to update its values and vision, including through better integration of human security thinking, if it is to retain the leadership role it acquired thanks to Haq

    Ab initio study of the structure, elastic, and electronic properties of Ti3(Al1−nSin)C2 layered ternary compounds

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    The MAX phase materials such as layered ternary carbides that simultaneously exhibit characteristics of metallic and ceramic materials have received substantial interest in recent years. Here, we present a systematic investigation of the electronic, structural stabilities, and elastic properties of Ti-3(Al1-nSin)C-2 (n=0,1) MAX phase materials using the ab initio method via a plane-wave pseudopotential approach within generalized-gradient-approximations. The computed electronic band structures and projected density of states show that both Ti3SiC2 and Ti3AlC2 are metallic materials with a high density of states at the Fermi level emanating mainly from Ti-3d. Using the calculated elastic constants, the mechanical stability of the compounds was confirmed following the Born stability criteria for hexagonal structures. The Cauchy pressure and the Pugh's ratio values establish the brittle nature of the Ti3SiC2 and Ti3AlC2 MAX phase materials. Due to their intriguing physical properties, these materials are expected to be suitable for applications such as thermal shock refractories and electrical contact coatings
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